
Class _IX^S3- 

Book ,rS £ 

Copyright N°_ 

COPYRIGHT DEPOSm 



SHORT COURSE 



FOR 



JANITOR -ENGINEERS 



BY 



KENNETH G. SMITH, C. E. 




THE BRUCE PUBLISHING COMPANY 
MILWAUKEE, WIS. 






^ 



Copyright 1919 
The Bruce Publishing Co, 



MAR 17 1919 
©CU5 12650 



INTRODUCTION 



The janitor of a school or other public building occupies 
a position of more responsibility than is usually recognized. 
He is in a very real sense responsible for the health and com- 
fort of the occupants of the building under his care. He is 
also responsible for the economical use of fuel, equipment 
and supplies. To discharge his duties properly he needs 
technical knowledge and practical experience. 

Up to the present time no attempt has been made to 
formulate and offer any definite course of instruction for the 
janitor-engineer. Usually verbal directions have been given 
as to what he is expected to do, sometimes accompanied by a 
"book of rules." The reasons for these rules he may or may 
not understand. To add to his difficulties he is often required 
to take orders from, or at least to accede to the requests of, a 
number of persons, some of whom, at least, know less about 
his duties than he does. Again, the entire responsibility of 
running a plant may be thrown on his shoulders with the one 
admonition that he "will be held responsible" if anything 
goes wrong. 

The work of a janitor is a real vocation requiring, as it 
does, technical knowledge, a knowledge of human nature and 
ability to get along with people, and, especially in the 
schools, the exercise of discipline. There is no reason why 
the calling of the janitor-engineer should not have a place in 
the present program of vocational education, and it was in 
connection with such a program that the following text was 
first prepared and used. It may serve as a reference book to 
be read by a janitor during his leisure moments (if he has 
any) or it may be used as the basis of a definite course of 
instruction in an evening or day class under a regular in- 
structor. 

3 



The text in its present form is not as complete as the 
writer would like to have it and it is his purpose to revise and 
extend it as soon as possible. Owing to the fact that fuel 
saving is now a national issue considerable attention has been 
paid to this subject. No claim is made for originality. The 
book is not the result of technical research. It is simply an 
adaptation of many facts already well known. Acknowledg- 
ment is hereby made to the many chief engineers and members 
of school boards and school faculties who have put their in- 
formation and experience at my disposal as well as to many 
janitor-engineers whom I am proud to call my friends. 

KENNETH G. SMITH, M. E. 



Table of Contents 

Introduction 



Chapter I. 
HEAT — Thermometers — Heat Measurement — Effects of Heat 

— Questions 7-14 

Chapter II. 
PROPERTIES OF HEAT — How Heat Travels — Circumstances 

Affecting Heat Travel — Latent and Sensible Heat — Questions. 15-23 

( 'Iiapter III. 
COAL AND COMBUSTION — Characteristics of Coal — Analysis 
of Coals — Names and Sizes of Coals — Combustion — Con- 
ditions Necessary for Combustion — - Questions 24-34 

Chapter IV. 
METHODS OF FIRING — Smoke Prevention — Causes of Smoke 

— Methods of Firing — Keeping a Good Fire — Special 
Methods and Appliances — Clinkers — Banking Fires — 
Questions 35-46 

Chapter V . 
THE HEATING PLANT — Boilers — Washing Boilers — Boiling 
Out — Scale and Its Removal — Laying up a Boiler — Heat- 
ing Plant Definitions — Steam Heating Systems — Placing 
Radiators— Direct and Indirect Systems — Warm Air Systems 

— Questions 47-58 

Chapter VI. 
GOOD AND BAD AIR — Air Space Requirements — Air Supply 
Requirements — Air Distribution — Temperature — Types 
of Ventilating Systems — Types of Fan Systems — Natural 
and Aspiration Systems — Operation of Fan Systems — Con- 
clusions of Chicago Commission on Ventilation in Regard to 
Schoolroom Heating and Ventilation — Questions 59-73 

Chapter VII. 
HUMIDITY — Relative and Absolute Humidity — Humidity 
Tables — Effects of Humidity — Measuring Humidity — Sup- 
plying Moisture to Air — Air Washers — Conclusions of the 
Chicago Commission on Ventilation in Regard to Humidity 

and Temperature — Questions 74-85 

5 



6 Table of Contents — Continued 

Chapter VIII. 

SWEEPING, CLEANING AND SANITATION — Sweeping and 
Cleaning — Sweeping — Special Methods of Cleaning — Sani- 
tation — Health and Cleanliness — Disinfectants and Their Use 
— Rules and Regulations for Cleaning and Care of School 
Buildings and Grounds — Rules for Building Care — Winter 
Care 86-98 

JANITOR'S CATECHISM — School Environment 99-100 

LIST OF BOOKS FOR JANITOR-ENGINEERS 101 



A Short Course for Janitor- Engineers 

i 

The duty of a janitor or custodian of a building is to take 
care of the building and to conserve the health and comfort 
of the occupants. One of his main duties, especially in the 
winter time, is to keep the building at a proper temperature ; 
in other words, to provide heat. Heat, then, is one of the 
fundamental things for a janitor to understand. Scientists 
at the present time explain heat by what is known as the 
kinetic or motion theory. All substances are supposed to 
be made up of very small particles called molecules. Ac- 
cording to the kinetic theory of heat, these particles are 
continually in motion and the faster they move the hotter 
we say the body is. In very hot steam they are supposed to 
move very rapidly and comparatively long distances. In 
cold iron they move more slowly and shorter distances. Our 
sense of feeling tells us whether this motion is slow or rapid 
or in other words whether the body is cold or hot. If we de- 
sire to know accurately how warm a substance is we use a 
thermometer and do not depend upon our sense of feeling. 

Thermometers 

Every janitor is familiar with the fact that "feelings" 
are not always a safe guide in determining the temperature 
of a room. One person coming in from the outer air will con- 
sider the room to be warm; another accustomed to a high 
temperature will say the room is cold. Hence, the need of 
the thermometer. There are two common kinds of thermo- 
meters, the Fahrenheit and the Centigrade. The Fahrenheit, 
so named from its inventor, is most commonly used except 
for scientific work. The word "centigrade" means "scale of 
one hundred" and is so named because there are one hundred 
degrees on it between the freezing and boiling points of water, 
as will now be explained. 

7 



8 A Short Course for Janitor-Engineers 

Every thermometer must have certain fixed points upon 
it from which the divisions or degrees are marked. For this 
purpose we use the freezing and boiling points of water under 
standard conditions. On a Fahrenheit thermometer the freez- 
ing point is 32° above zero and the boiling point 180° above 
the freezing point, or 212° above zero. On a Centigrade 
thermometer the freezing point of water is marked and the 
boiling point 100 and there are of course then 100 degrees 
between them. For this reason the thermometer is called 
Centigrade, as mentioned above. The word "cent" or "cen- 
tum" means one hundred and is used in our common words 
cent and per cent. The boiling point of water is not always 
212° because it depends upon the pressure on the water. At 
sea level, where the atmospheric pressure is greatest, the 
boiling point is 212°. On top of a mountain, where the at- 
mospheric pressure is less, the boiling point is lower. In round 
numbers, we may say that the boiling point drops 1 ° for every 
500 feet elevation. In Cedar Rapids, Iowa, the boiling point 
is about 211°. For practical purposes we consider it to be 
212° Fahrenheit or 100° Centigrade. 

We are so accustomed to thermometer readings that we 
know instantly when a temperature is mentioned whether 
we consider it hot or cold. Air temperatures affect our 
comfort, though our feelings are not an accurate measure of 
temperature. Twenty degrees below zero or -20° we consider 
very cold, 110° above zero we consider very hot. A room 
temperature of 65° to 70° we consider comfortable, though 
we shall learn later on that other things besides temperature 
affect our comfort in a marked degree. To indicate room 
temperature properly a thermometer should be placed on an 
inside wall not exposed to drafts of cold or warm air and not 
in an air pocket where there is little or no circulation. 

Sometimes thermometers are suspended by a cord in 
the center of a room about five feet above the floor. In this 
position they give a better reading of average room tempera- 



Heat Measurement 



9 



ture, but are inconvenient and troublesome for persons 
passing back and forth. 

Heat Measurement 

When the question is asked, "How is heat measured?" 
one naturally answers, "In degrees." This is not the case, as 




I 



CENTIGRADE 5CALE 
FAHRENHEIT 

Melting paint of common so/der 3b5 



Soifinq point of woftr dtnormoi 'pressure 
2oo Zl2 ° 



,00 Aiorrnol temperature of human body 

98.6' 

Txooms where occupants are riot etercnina 

so 68" 

frees/no paint of water 32" 

to ' 

o 

■o 

to -xa* 

Freezing pomr of mercury — Jo 



TABLE 

OF 

USEFUL TEMPERATURES 



Mercury freezes 

Treezintj cold storage 
Water freezes 



I 



iDanaer of frost- 
Household refrigerator- 
Rooms vjhere occupants, 
are not exercising 
Gymnasium. 



Human body normoL 
Wafer boils ot 

normal pressure 

He/ting point of 

common Soft so/Je r 
A/eifi/fa point of lead. 



"enf- 
graJe 

-39 



fvhren 
heif 

-38 



~/6 



±4. 



13 



20 



Zl 



13 



31 



too 



185 



321 



±12 



Ji 



39 



+5 

55 

68 

JO. 



55 
t8b 



212 



365 



6ZI 



Fig. 1. Fahrenheit and Centigrade Scales. 



10 A Short Course for Janitor-Engineers 

a little thought will show. Measuring heat in degrees would 
be like measuring water in inches. Three inches of water 
does not give us any definite idea of the quantity of water 
present, neither does the expression 60 degrees of heat give 
us any idea of the quantity of heat present. In order to have 
a definite idea of the amount of water indicated by three 
inches, we must know in what the water is contained. If 
the containing vessel is a small tin cup, we know that three 
inches of water is a small amount. If the vessel is a huge tank 
we know that three inches of water is a large amount. Just 
so with heat. Sixty degrees may represent a large or small 
quantity of heat, depending on what contains the heat. The 
standard substance in which to measure heat is water and 
engineers have decided to call the amount of heat necessary 
to raise one pound of water one degree Fahrenheit one heat 
unit or British Thermal Unit, usually abbreviated B. t. u. 
Two heat units would raise two pounds of water one degree 
or one pound two degrees. This B. t. u. is a very definite 
quantity applied to the measurement of heat, just as definite 
as the pint applied to the measurement of water. The re- 
lation between heat and temperature is also evident. To raise 
40 pounds of water 10 degrees requires 40X10 = 400 B. t. u. 
It would require the same amount to raise 20 pounds 20 de- 
grees (20X20 = 400) or 10 pounds 40 degrees (10X40 = 400). 
In the same way 400 pints of water might fill a large tank to 
a depth of six inches, a smaller tank to a depth of 12 inches, 
and a still smaller one to a depth of 24 inches. The quantity 
of water, like the quantity of heat, remains the same in all cases. 
There is, however, an additional and very practical 
point to be noted about heat. Different substances require 
different quantities of heat to raise one pound one degree. 
We are all familiar with this fact, though we may not realize 
it. We say that certain substances heat up quickly or cool 
off quickfy, meaning that it requires only a small amount of 
heat to raise their temperature and that they give off but 



Specific Heat of Substance 1 1 

little heat before they become cold. The number of heat 
units required to raise one pound of a substance one degree 
is called its specific heat. The specific heat of water is one 
because it requires one heat unit to raise the temperature of 
one pound one degree. The specific heat of cast iron is 
0.129, meaning that it requires 0.129 heat units to raise 
a pound of cast iron one degree in temperature. The 
specific heat of lead is 0.031, hence, lead heats up very 
rapidly. The specific heat of brick work and masonry 
is about 0.20. The specific heat of air at atmospheric pressure 
is 0.238, that is, a pound of air heats up about four times as 
fast as a pound of water. This is one reason why a warm air 
system heats up so much more quickly than a hot water 
system and also the reason why it cools off more quickly, as 
everyone knows. Only two known substances heat up more 
slowly than water, that is, have a higher specific heat than 
water, hydrogen and bromine. As these are not substances 
with which we have to deal, we shall let them pass without 
further discussion. 

The following is a table of the specific heats of a few com- 
mon substances. Note that B. t. u. stands for British Ther- 
mal Unit. 

B. t. u. 

Water 1 

Cast iron 0.129 

Copper 0.095 

Lead 0.031 

Brick work 0.195 

Masonry 0.215 

Pine wood 0.467 

Oak wood 0.570 

Plaster 0.20 

Air 0.237 

From such a table as this we can see the reason why a 
building heated once a week, like a church for instance, re- 



12 A Short Course for Janitor-Engineers 

quires so long to heat up. Not only the air, but the walls, 
radiators, seats and flooring must all be heated up. Cold 
radiators condense a large amount of steam, as every janitor 
knows. Let us suppose that a cast iron radiator weighing 
500 pounds stands in a building where the temperature has 
dropped to 40°, how many heat units will it take to raise its 
temperature to 212°? 

212° -40° =172° rise in temperature. 

To raise one pound of cast iron one degree requires 0.129 
B. t. u.; to raise one pound 172 degrees requires 172X0.129 = 
22.188 B. t. u. 

To raise 400 pounds 172 degrees requires 22.188X400 = 
8875.2 B. t. u. This would be all the heat that could be ob- 
tained for heating purposes by burning one pound of average 
soft coal. You can easily see why cold radiators require the 
expenditure of a large amount of fuel to heat them up. 

The Effects of Heat 

All of us are more or less familiar with the effects of heat 
on different substances. The most common effect is expansion 
of the substance. Steam pipes expand and, if allowance is 
not made, such expansion results in warped and broken pipes 
and fittings. Brass expands more than iron or steel and for 
this reason brass bushings which are heated and cooled be- 
come loose. In allowing for expansion, it is safe to consider 
that a low pressure steam pipe will increase in length, when 
heated up to steam temperature, 1-64" for every foot. If 
one part of an object is heated so quickly that the heat does 
not have time to travel throughout the substance and produce 
an even temperature, we have unequal expansion, causing 
expansion stresses, which often are very severe. For this 
reason a boiler, especially a new boiler, should be fired up 
slowly, so that no portion may become overheated. For the 
same reason an engine is always gradually warmed up before 
starting. Frozen pipes are sometimes cracked by a blow 



Effects of Heat 13 

torch if heated too quickly on the outside. Glass bottles, 
tumblers and water-gauge glasses are often cracked by too 
sudden heating or cooling in one spot. The remedy in all 
these cases is to heat or cool gradually. 

Water is peculiar. If it is heated from 32° to 39° it con- 
tracts slightly. If heated above 39° it expands. A cold boiler 
filled with water and heated shows a higher level in the gauge 
cocks and water-glass than before the fire was started, because 
of this expansion. Water heated above 39° tends to go to 
the top of the vessel in which it is contained because on ac- 
count of its expansion it becomes lighter, that is, weighs less 
per cubic foot. The fact that hot water rises is an important 
point to be remembered in piping all forms of hot water heat- 
ing appliances. In freezing, water expands nearly 1-10 of 
its volume and if closely confined bursts the containing vessel. 
Bursted pipes bear witness to this fact. Water which has 
been heated freezes quicker than fresh water, due to the fact 
that there is less air in it. This accounts for the statement 
often made, "Hot water pipes freeze quicker than cold water 
pipes." 

Air also expands and becomes lighter when heated. This 
causes the draft in a chimney, for the cold air rushes in and 
pushes the warmer, lighter air out. In a room the warmest 
layer of air is next the ceiling, the cold air is on the floor. 
These facts must always be borne in mind when ventilating 
a room by windows. Windows open at the top cool the room 
off rapidly and make it difficult to heat, for the warmed air 
rises and passes out as fast as it is heated. 

Questions 

1. What are the two kinds of thermometers commonly used? 

2. What are the freezing and the boiling points of water on each of 
these thermometers? 

3. How is quantity of heat measured? 

4. What do you mean by the specific heat of a substance? 

5. Why does a hot water system heat up and cool off slowly? 



14 A Short Course for Janitor-Engineers 

6. Why does a warm air system heat up and cool off rapidly? 

7. How would you prevent water pipes from freezing? Give at 
least two methods. 

8. What do you consider to be the best method of thawing frozen 
pipes if they are accessible? 

9. At what temperature would you keep a manual training shop 
in which boys are working? 

10. At what temperature would you keep the halls of a school 
building? 

11. Suppose a boiler to be hot and the water low, what is the effect 
of rapid filling under these conditions? 

12. Explain two methods of providing for expansion in a short 
run of pipe? 

13. How is the expansion of water provided for in a hot water 
system? 

15. A teacher sitting on the platform at one end of the room says 
the room is too warm. The thermometer in the main room shows 68°. 
What is one good reason for this condition? 



II 

HOW HEAT TRAVELS 

Heat travels from one part of a substance to another or 
from one object to another, as you know if you heat a poker in 
fire, warm your feet at the register or burn your finger on 
the stove. The important point to be noted is that heat al- 
ways travels or flows from a higher temperature to a lower 
temperature just as water flows from a higher level to a lower 
level. Heat never flows from a low temperature to a high 
temperature. In other words, a room cannot be heated if 
the stove or radiators in it are no warmer than the room. 
The hotter they are, the faster the heat flows from them to 
the room. Always bear in mind that there is no such thing 
as "cold" and that "cold" does not travel. Heat travels, 
cold does not. In a thermos bottle filled with ice cream the 
cold does not come out. The heat goes in (slowly) from 
the outside and thaws the ice cream. If the same bottle is 
full of hot tea the heat travels out and the tea cools off. The 
purpose of the vacuum jacket or insulating material is to keep 
the heat from traveling out or in, according to whether the 
high temperature is inside or outside. We put building paper 
on our walls, use double windows, and cover our steam pipes, 
not to keep cold out, but to keep the heat in. We may put 
weatherstrips or metal strips around windows and doors and 
stop up cracks to prevent cold air coming in. These do not, 
however, keep the "cold" out. They do help to keep the warm 
air in for whether the air comes in or goes out of a window or 
crack depends upon whether the air pressure is greater out- 
side or inside the building and not upon the difference in 
temperature. 

There are three methods of heat travel or heat trans- 
mission, as it is usually called, with which we are familiar and 
which we recognize as soon as pointed out. These three 
methods of heat travel are : 

15 



16 A Short Course for Janitor-Engineers 

1. Conduction. 

2. Convection. 

3. Radiation. 

Heat is conducted from the hot part of a substance to a 
colder part of the same substance or to another colder sub- 
stance. Every fireman knows that when he runs one end of 
the slice bar or poker into the fire the other end gets hot. Heat 
is conducted from one end of the bar to the other. In a boiler 
the heat is conducted from the outside or fire side of the shell 
through the iron to the water on the inside. Heat is con- 
ducted from the inside of a radiator to the outside. Other 
examples of conduction will suggest themselves. Note that 
when heat travels by this method the particles of the substance 
do not move perceptibly. 

Heat may be carried from one part of substance to another 
by the actual movement of the particles. This method of 
heat travel is known as convection or carrying. Naturally 
heat does not travel by this method in solid substances 
like iron, copper or lead, because the particles cannot move. 
Beat travels by convection or canying in liquids, like water, 
or gases, like air. The air of a furnace is heated in the base- 
ment and actually carries the heat to the floors above. We 
say the air "circulates." If it does not circulate the heat 
cannot be carried, the room does not warm up and the furnace 
fails. Heat is carried in the same way by the hot water in a 
hot water system or by the steam in a steam system. In 
each case the steam or water carries its load of heat to the 
radiators and "dumps it" so to speak, and returns to the 
boiler for another load. If there is no circulation there is no 
heating. A boiler which has poor circulation will not steam 
well. 

The third method by which heat travels is radiation. 
By this method heat is shot out in straight lines from the 
surface of hot objects and strikes and heats other objects. 
Heat is radiated or shot out from the side of a hot stove or 



How Heat Travels 17 

radiator and we feel the burning sensation on our hands and 
faces. As you walk by a red hot stove or open fire you put 
up your hand or cap to shield yourself from the heat shot out 
or radiated from it. Heat which is radiated does not heat the 
air effectively through which it passes. This is why an open 
fire may scorch one's face and yet one's legs and body feel 
uncomfortably cold. The air of the room is not being heated 
well because the heat is radiated or shot through it directly 
to the objects in the room. Heat is radiated from the sun. 
Stones, bricks and metal placed in the sun become hotter 
than the surrounding air. In the ordinary steam radiator the 
three methods of heat transmission are illustrated. The heat 
is brought into the radiator by the steam by the method of 
convection. It is conveyed from the inside of the radiator, 
to the outside by conduction and is delivered to the room 
partly by convection (circulation of air) and partly by radia- 
tion. See Fig. 2. 

Circumstances Affecting Heat Travel 

Substances vary greatly in their ability to conduct heat. 
In general it may be said that solids, especially metals, are 
good conductors of heat, liquids are not so good and gases are 
the poorest conductors of heat. Some solids are not good 
conductors of heat. Such substances as magnesia block, 
asbestos cement, hair felt, cork and wood are used for pipe 
coverings so as to keep the heat in. The thicker the substance 
is, the harder it will be for the heat to get through it. For 
this reason a boiler shell cannot be made too thick or the heat 
will not be transmitted easily to the water. Glass is not a 
good conductor of heat, but nevertheless heat will be trans- 
mitted through a single window about four times as fast as 
through a wall, because the glass is so thin. This partially 
accounts for the fact that rooms having a large number of 
windows are hard to heat. Dead air space is a very poor con- 
ductor of heat, hence an air space between two walls in a 




Air currents 
carrying heat -connection 



Radioted 
heat -radiation 



Heat conducted 
through iron fo outer 
surface - Conduction. 



HOW A RADIATOR HEATS 

5zi 



Window open 
at top 




How heat 
may be wasted 
oy connect/on currents 

r,g 3 




COWECTlON CURRCNT5 
AIDING /A/ HEATING 
F/Q 4 




"Empty buckets 
refi/rn/na (water) 



LATENT HEAT 
CARRIED Br STE/4M 



rig 5 



18 



Heat Conductors and Non-Conductors 19 

building or between two double windows aids in keeping heat 
in. For the same reason a dead air space in a radiator pre- 
vents its heating and we say the radiator is "air bound." 
The air will not let the hot steam enter the radiator and will 
not conduct the heat from the steam through the radiator. 
Soot and scale are very poor conductors of heat, hence every 
effort should be made to keep them off boiler surfaces. One- 
sixteenth inch of scale or soot is said to diminish the con- 
ducting power of a boiler tube 25%. For the same reason 
the pipe coverings should be kept in good condition, so as to 
prevent the escape of heat. In one case we remove the 
covering so as to allow free passage for the heat; in the 
other we keep the covering in good shape in order to obstruct 
the passage of heat. Fireless cookers are built solely for the 
purpose of keeping heat in. 

Radiation takes place from the surface of a substance 
and the condition of the surface as well as the material affects 
its radiating power. In general, highly polished, light colored 
surfaces will not radiate heat so well as dull, dark colored 
surfaces. Stoves and steam pipes should be black if they are 
intended to give out heat, but hot air pipes, cooking utensils 
should be brightly polished in order to lose as little heat as 
possible. A nickel plated stove will be about half as effective 
as a black stove of the same temperature. Bright tin warm 
air furnace pipes often lose less heat bare than they do when 
covered with one or two layers of asbestos paper, since the 
paper radiates the heat so much more than the tin as to more 
than balance the effect of the thin asbestos covering. The 
insulating covering should be f " thick or more to save heat on 
a bright tin pipe. A simple experiment shows the difference 
between the heat radiated from a black surface and a polished 
surface very clearly. Take a new tin shingle and smoke one 
side over an open kerosene flame until it is black. Leave the 
other side clean. Heat the shingle on a stove or clean flame. 
Have some one hold the shingle between your open palms 



20 A Short Course for Janitor-Engineers 

about an inch from each. The difference in the heat radiated 
from the two surfaces is very noticeable. 

Another point to be noted is that the rate at which heat 
is transmitted depends on the difference in temperature, 
just as the rate at which water flows depends on the difference 
in level. If, on a mild day in winter, the temperature is 50° 
outdoors and 70° inside the building, the difference is 20° 
and the heat will pass out through walls and windows at a 
certain rate. If, on the next day, the outdoor temperature 
goes down to 30°, the difference is 40° and the heat will pass 
out approximately twice as fast. We say approximately, 
because we know that the rate of heat transmission increases 
faster than the difference in temperature. Some engineers 
state that it requires 25% more fuel to keep a building at 70° 
than it does to keep it at 60° in cold winter weather. Hence, 
to save fuel, rooms should be kept at as low a temperature as 
possible consistent with health and comfort. 

Latent and Sensible Heat 

So far in discussing heat we have assumed that it always 
raises the temperature of substances. This is not always the 
case. Heat may change the state of a substance. It may 
change ice to water, melt the ice, or it may change water to 
steam, evaporate the water. When heat is changing the 
state of substance, it does not raise its temperature. To prove 
this, place a mixture of ice and water in a cup and take its 
temperature. The thermometer will show 32°, the freezing 
point of water or melting point of ice. Place the cup on the 
stove and stir the mixture continually. The temperature will 
remain at 32° until the ice is all melted. The reason is that the 
heat is all used in melting the ice. It cannot raise the tempera- 
ture until the melting is all done. It requires 142 heat units to 
melt a pound of ice. This heat is known as the latent heat of 
fusion or melting. To continue this experiment after the ice 
is melted heat the water until it boils at approximately 212°. 



Latent and Sensible Heat 21 

Here, again, the thermometer stops rising and the water 
changes to steam. The heat going into the boiling water is 
all used in evaporating the water and cannot raise the tem- 
perature as long as the water is in an open cup. This heat 
is called the latent heat of evaporation. It takes 970.4 B. t. u. 
to evaporate one pound of water at atmospheric pressure. 
This latent heat is all given up by the steam when it condenses 
back to water and this heat is what is used in a steam heating 
system. If water is in a boiler under pressure it can be heated 
hotter than 212°. Every pressure has a certain fixed tempera- 
ture which never varies. The pressure, temperature and 
latent heat of steam are all given in what are called 
steam tables. These are very important for the stationary 
engineer to understand and they should be understood, at 
least in part, by the man who runs a heating system. The 
following is part of a steam table showing the properties of 
steam from one to five pounds pressure, which would be within 
the limits of most heating systems. 





Temperature 


Latent Heat 


ressure lbs. 


Degrees 


B. t. u. per lb 





212° 


970.4 


1 


215 


968.23 


2 


219 


966.2 


3 


221 


964.27 


4 


224 


962.4 


5 


227 


960.6 



Note carefully that as the pressure increases the tempera- 
ture of water and steam increases. High pressure steam is 
hotter than low pressure steam. The column headed "Latent 
Heat, B. t. u. per pound" tells just how many heat units 
are given to the radiator when one pound of steam is con- 
densed at that pressure. For instance, if one pound of steam 
at or atmospheric pressure is condensed as in a vapor system, 
970.4 B. t. u. are given to the radiator to be carried into the 



22 A Short Course for Janitor-Engineers 

room. Now note that if steam at three pounds pressure is 
condensed only 964.27 B. t. u. are given up. High pressure 
steam does not have so many heat units to give up for heating 
as the low pressure steam. This is one advantage of low 
pressure steam for heating purposes. High pressure steam will 
heat faster, but more pounds must be circulated to carry the 
same number of heat units to the room. The important 
point to remember is that steam must be condensed in order 
to get the heat out of it. Heating with steam might be com- 
pared to carrying water in buckets on an endless chain. 
Every pound of steam circulated represents one bucket. 
Condensing a pound of steam is the same as dumping a bucket. 
High pressure steam would be represented by small buckets 
running at a rapid rate. Low pressure steam would be repre- 
sented by larger buckets running at a slower rate. See Fig. 5. 
In an ordinary steam heating system one square foot of 
direct radiation will condense about one-fourth of a pound of 
steam per hour. This means that each square foot of radia- 
tion is capable of supplying about 240 B. t. u. every hour 
to the room. 

Questions 

1. Explain why a room in which there is no circulation will not 
heat. If you found a room difficult to heat on account of air pockets and 
dead air spaces, what would you do? 

2. Why are rooms with high ceilings difficult to heat? 

3. A display window in a large building was continually covered 
with frost in cold winter weather. The owner was advised to use an 
electric fan. Explain how this would prevent frost from gathering. 

4. A building is heated by steam sent directly through the coils 
without returning to the boiler. Engineer A says he can heat the building 
faster by blowing steam through rapidly so that live steam flows from the 
outlet. Engineer B says he can heat faster by allowing the steam to con- 
dense. Which is right? Which is more economical? 

5. Some persons recommend putting a tub of water in the cellar 
to prevent the freezing of vegetables. Is there any good reason for this? 
Explain. 



Questions on Heat 23 

6. The pupils in a certain building heated by stoves complain of 
the heat when seated near the stove. Suggest a remedy for this condition. 
Draw a rough sketch of your idea. 

7. Will a building which is cold in winter be cool in summer as a 
general rule? Why? 

8. A large smoke pipe passes through a certain room. It is desired 
to utilize the heat from this pipe to warm the room. Should the pipe be 
bright, galvanized iron or painted black, and why? 

9. Why do aluminum utensils heat up so quickly and uniformly? 
What is the reason for putting a wooden handle on a poker? 

10. When the temperature is the same on both sides of a building, 
why is the side toward the wind harder to heat? 

11. Engineer A says, "Never open a window over a radiator, it 
cools the radiator off." Engineer B says "Always open a window over a 
radiator if you can." Which is right? 

12. Explain the precautions you would take in putting on double 
windows in order to secure the best results. 

13. Do the metal shields sometimes placed behind steam radiators 
increase or decrease the heat given off and why? 



Ill 

COAL AND COMBUSTION 

The heat supplied to a building is usually obtained by 
burning coal and therefore every janitor, or at least every 
fireman, should know something about the composition and 
properties of coal. Coal, as we shall consider it, is made up 
of four different substances : 

1. Carbon, 

2. Gas, 

3. Water, 

4. Ashes. 

Of these substances, the carbon and most of the gas are 
combustible; that is, they will burn; the water and ashes will 
not burn. Carbon is the solid combustible matter in the coal, 
the burning of which produces most of the heat. Coke, 
charcoal and graphite are other common forms of carbon. 
The gas found in coal is chiefly in the form of compounds of 
hydrogen and carbon, called for short hydro-carbons. These 
hydro-carbons burn with a very hot flame and hence are a 
valuable part of the fuel. Water and ashes are found in all 
coals in varying quantities. In addition to the substances 
mentioned some coals contain sulphur. Sulphur will burn, 
but does not produce much heat and is an undesirable element 
in coal, due to the fact that, when burned, the gas formed 
mixes with the moisture from the coal or steam from the ash 
pit and forms an acid which corrodes the grate bars. 

To determine the characteristics of any kind of coal it 
is necessary to find out in what proportions the substances 
contained are present. To do this a chemical analysis is made. 
The one most useful to engineers is known as the proximate 
(approximate) analysis. This tells simply how much carbon, 
gas, water, ashes and sulphur are in the coal. The chemical 
terms used are the following : 

24 



Characteristics of Coal 



25 



r 



3&5Z, 



50 F T COAL. 

A 



ILLINO IS 



fig ff 



Pennsy I von 1 a 
hard cool 



\6as{\ 




COMPOSITION OF TYPICAL COALS. 



Carbon — Fixed carbon. 
Gas — Volatile matter. 
Water — Moisture. 
Sulphur — Sulphur. 

The "fixed carbon" is called " fixed" to distinguish it 
from the carbon combined with the hydrogen in the gaseous 
hydro-carbons, which pass off when the coal is heated. Coke 
is coal from which all gas and moisture have been driven off 
by heat and consists of fixed carbon and ash. 

We are accumstomed to divide coal into two classes, 
hard and soft. Speaking more scientifically, we may say that 
there are three general classes of coal: Anthracite, or hard; 
semi-bituminous, or moderately soft, and bituminous, or soft 



26 A Short Course for Janitor-Engineers 

coal. The difference between them is in the amount of volatile 
matter contained. Hard coal contains very little volatile 
matter, semi-bituminous contains more and common bi- 
tuminous or soft coal contains a large proportion. The aver- 
age proportions of different substances in coals of the different 
classes are shown in Fig. 6. 

The amount of volatile matter contained in a coal is a 
very good indication of its smoke producing properties. Coals 
containing much volatile matter are hard to burn without 
smoke. "Smokeless" soft coals are simply soft coals contain- 
ing a small amount of volatile matter. 

Bituminous Coal 

Bituminous coals are subdivided into caking and non- 
caking coals. Caking coals are those which melt and run 
together when thrown on the fire, thus forming a blanket 
or cover over the fuel bed on which blisters or puff balls of 
gas form. These burst and allow the gas to escape and burn 
with a bright yellow or reddish flame. These coals usually 
contain a large amount of gas and for that reason are valuable 
for gas making. Non-caking coals do not melt and run to- 
gether when heated and are sometimes called "free burning" 
coals for this reason. They make good fuel for heating and 
power plants. They may be distinguished by the fact that 
they break in layers and the broken surface at right angles to 
the layers appears bright and shiny. Semi-bituminous coals, 
mined chiefly in the East, make a very hot fire and but little 
smoke. Pocahontas is a good example of this type of coal. 
Hard coal is too well known to need further description. 

To show what his coal is made of, a dealer furnishes an 
"analysis," that is, a table showing what the coal contains. 

The easiest way to get a clear idea of the meaning of 
these percentages is to consider that the columns headed 
moisture, volatile, fixed carbon and ash represent the number 







Coal Analysis 






27 




PROXIMATE ANALYSIS OF 


REPRESENTATIVE COALS 








Fixed 






Heating 




Moisture 


Volatile 


Carbon 


Ash 


Sulphur 


Value 




% 


% 


% 


% 


% 


% 


1. 


Hard 5.41 


7.03 


71.79 


15.78 


.743 


12047 


2. 


Semi-bituminous. . 1 .63 


17.17 


75.34 


5.86 


.75 


14672 


3. 


Bituminous 12.39 


36.89 


[41.80 


8.92 


3.92 


11399 


4. 


Bituminous 14.21 


33.17 


37.40 


15.22 


4.66 


10019 


5. 


Bituminous 7.91 


37.94 


45.02 


9.13 


3.62 


12200 



of pounds of the substance in 100 pounds of coal. That is, 
in 100 pounds of coal No. 1 there are 5.41 pounds of water, 
7.02 pounds of gas, 71.79 pounds of fixed carbon, and 15.78 
pounds of ashes. These, added together, make 100 pounds. 
In this 100-pound lump of coal is 0.743 of a pound of sulphur. 
Sulphur is usually taken out separately and is said to be 
"separately determined." Glancing at coal No. 1 you will 
note that about one-fifth of it is water and ashes. At $8.00 
per ton one would pay $1.60 for water and ashes. 



Conclusions from Analysis 

In drawing our conclusions from a coal analysis, we may 
say that a high percentage of volatile matter indicates that 
the coal must be carefully fired in order to get good efficiency 
and avoid making smoke. Coals low in volatile matter do not 
require such careful firing. Coals high in ash increase the work 
of ash removal and of course do not contain so much combus- 
tible matter. Coals containing a high percentage of moisture 
cause loss of heat because the heat required to evaporate the 
moisture in the furnace cannot be given to the boiler. There 
may, however, be reasons for wetting the coal as we shall see 
later on. Sulphur, as has been said, is an undesirable element. 
The last item, "the heating value," is an important one. 
Heating value means the number of B. t. u. developed by 
burning completely one pound of coal. For instance, the 



28 A Shwt Course for Janitor-Engineers 

heating value of sample No. 3 above is 11,399 B. t. u. This 
means that one pound of this coal completely burned would 
develop 11,399 B. t. u. Referring to the definition of B. t. u. 
this means that the heat is sufficient to raise 11399 pounds of 
water 1°, or 1 pound of water 11399°. A boiler and furnace 
cannot make use of all the heat units in the coal, for some are 
lost up the stack, some are radiated from boiler front, pipes 
and setting out into the boiler room, and some are lost in un- 
burned fuel in the ashes. In fact, if the average boiler makes 
use of 60% to 65% of the heat units in the coal it is doing well. 
The duty of the fireman is to see that as large a proportion of 
the heat as possible is utilized, since the per cent of the total 
heat in the coal present in the steam delivered to the heating 
system is a measure of the efficiency of the boiler and furnace. 
In buying coal we are interested solely in buying heat 
which we can use. The coal which furnishes the greatest 
number of heat units for one cent is the cheapest coal to buy, 
provided it can be burned efficiently. Some furnaces are not 
adapted to burning cheap grades of coal and therefore waste 
a large amount of heat. In this case it is cheaper to buy a 
better grade of coal and use a larger percentage of the heat. 
For instance, suppose that coal No. 2 above cost $5.75 per 
ton of 2,000 pounds. The number of B. t. u. purchased for 

one cent is 14672X2Q0 ° = 51034. Taking coal No. 5 at $4.50 
575 

per ton to compare with it, the number of heat units for one 

L . 12200X2000 c , OQO T , , ,, . ., , , , 

cent is =54333. If both coals could be burned 

450 

equally well in the furnace, coal No. 5 would furnish more 
heat for the money. If, however, due to the construction of 
the furnace and draft conditions, only 60% of the heat units 
in coal No. 5 could be used, while 65% of the heat units in 
coal No. 2 were available, conditions would be reversed. 



Coal Sizes and Names 29 

51034 X .65 = 33172 B. t. u. actually used for every cent 
expended in the case of coal No. 2. 54333 X. 60 = 32599 B. 
t. u. actually used for every cent expended in the case of 
coal No. 5. Hence, in this case the high priced coal would 
actually be cheaper to use, due to the greater efficiency in 
burning it. This shows that the question of selecting proper 
coal is a complicated one and that actual boiler tests are 
necessary in order to determine the best coal for a certain 
plant. 

Names and Sizes of Coal 

Western soft coals are classified and known by the fol- 
lowing names: 

(1) Run-of-mine; the unscreened coal taken from the 
mine. 

(2) Lump coal; divided into 6-in., 3-in. and lj-in. 
lump, according to the diameter of the circular openings over 
which the grades will pass. Sometimes sizes are given as 
6x3-in. or 3xl|-in., meaning that the coal will go through the 
opening designated by the first figure and over the one desig- 
nated by the second. 

(3) Nut coal; divided into 3-in. "steam nut," lj-in. 
"nut" and f-in. "nut." 

(4) Slack coal; coal that passes through a f-in. opening. 

(5) Washed sizes; numbered 1, 2, 3, 4, 5, from the 3-in. 
size down. 

The common sizes of hard coal are: 1, buckwheat; 2, 
pea; 3, chestnut or nut; 4, stove or range; 5, egg. 

Coke is sized as follows: 1, pea f in. to \ in.; 2, nut 
f in. to \\ in.; 3, small stove \\ in. to 2 in.; 4, large stove 
2 in. to 2\ in. ; 5, egg 2\ in. to 3 in. 

In calculating sizes of bins for storing coal and coke we 
may take 40 cu. ft. of bituminous coal to one ton of 2,000 
pounds and 71 cu. ft. of coke to one ton. One ton of hard coal 
occupies approximately 37 \ cu. ft. Some soft coals when 



30 A Short Course for Janitor-Engineers 

stored in quantities in a bin or pile heat and take fire. Coals 
which break into fine dust are more apt to heat than those 
which do not. The following are some precautions to take 
when storing coal in order to avoid heating. 

(1) Store in small piles so that no part of the coal is 
more than 8 ft. from an air cooled surface. 

(2) Eliminate dust and fine coal so far as possible. 

(3) Store the coal dry. 

(4) Store so far as possible from external sources of 
heat, such as boilers and furnaces and hot cinder heaps. 

(5) Pile the coal evenly, not in a conical pile, and do not 
allow the dust to accumulate in the center with all the lumps 
around the edges. 

(6) Use the older parts of the storage first and do not 
allow old coal to accumulate in the corners and be covered 
by fresh coal. 

Combustion 

Knowing something about what coal is made of, we 
are now ready to take up the problem of burning coal. 
Combustion or burning is a chemical action accompa- 
nied by light and heat. The chemical action seen in 
burning coal is caused by the oxygen of the air uniting 
with the combustible substances in the coal. Air is not 
all oxygen, but approximately 1-5 oxygen and 4-5 nitrogen. 
The oxygen is the active agent in causing combustion; 
nitrogen simply accompanies the oxygen through the 
furnace unchanged and has no effect except to dilute the 
oxygen. Nothing is destroyed when coal burns. It is true 
that the coal disappears as coal. Different substances are 
formed and pass off as gas or remain in the ashes, and in this 
changing process heat is developed. This, to the fireman or 
engineer, is the important result. He is interested in the dif- 
ferent substances formed only as they indicate whether all 
the heat possible has been developed from the coal. 



Conditions Needed for Combustion 



31 



In order to have combustion three conditions must be 
fulfilled, which may be called the three "enoughs." 

1. There must be fuel enough. 

2. There must be air enough. 

3. There must be heat enough. 

A man who pays attention to the first condition only is 
a coal passer, not a fireman. A fireman knows that the 
second and third conditions are as important as the first for 
efficient combustion. The necessity for fulfilling all three 
conditions is well illustrated by the ordinary kerosene lamp. 
See Fig. 7. 



Heat 



Air 







V^ 



A/o Fue/ A/o Air 



A/o Heat 
J 



Fue/ 



Three conditions 
for combustion 



A/O COM BUS TlON 



Fig. 7 



If there is no oil the lamp goes out. If a tight cover is 
placed over the top of the chimney or the holes in the bottom 
of the burner stopped up, the lamp goes out for lack of air. 
The lamp cannot be lighted without a match, flame or some 
other source of heat. This is because the fuel must be made 
hot enough to burn. The temperature at which a fuel begins 
to burn is known as its "ignition point." We put the lamp out 
by blowing upon it to cool the wick and the fuel below the ig- 
nition point. These same three conditions must be fulfilled 
in a boiler furnace, as you will see if you think it over. The 
third condition is the one to be fulfilled when starting the 



32 A Short Course for Janitor-Engineers 

fire and the first and second concern the handling of the drafts 

and the coal scoop. The ignition point of carbon or the solid 

coal is about 750° F. and of most of the gases in coal about 

1100°. If cooled below these temperatures these substances 

will not burn. 

A furnace is not so easy to handle as a lamp and therefore 

efficient combustion is more difficult to secure. To make 

this clear, table No. 2 has been made out showing just what 

happens when coal burns. Note carefully that every pound 

of a combustible substance requires a definite, fixed amount 

of oxygen to burn it, which means a definite, fixed amount 

of air. A pound of carbon will burn with two definite amounts 

of oxygen or air, but will not burn with any more or any less 

than these fixed amounts. The following table states just 

how many pounds of air are required to burn completely a 

pound of the various substances in coal and what substance 

is formed. 

Table 2. 

Requires to burn A nd forms when 

One pound of completely burned 

Carbon 12 lbs. of air Carbon dioxide 

*Hydro-carbon 17 lbs. of air Carbon dioxide 

and water 

Sulphur 4 lbs. of air Sulphur dioxide 

Twelve pounds of air are approximately 150 cubic feet or 
the amount of air contained in a box 5' 4"x5' 4"x5' 4". 

Carbon dioxide is a colorless, odorless, suffocating gas 
found in the air, breathed out from our lungs, and also in the 
charged water obtained at soda fountains. It sometimes rises 
from the stomach into the nose after drinking a glass of soda 
water and causes a choking sensation. Sulphur dioxide is a 
gas with a very pungent odor. A sulphur candle, when 



* There are several hydro-carbons requiring different amounts of air. This is an 
average. 



Heat and Combustion 33 

burned, produces it in large quantities and it can also be de- 
tected whenever a sulphur match is lighted. 

Each pound of a substance when burned develops a 
certain amount of heat, as the following table shows. A pound 
of carbon will burn incompletely with just half enough air, 
that is, with six pounds instead of twelve, but in so doing does 
not give nearly so much heat. Hence, the necessity for com- 
plete combustion. 

Table 3. 

One pound of In burning develops 

Carbon (completely burned) 14500 B. t. u. 

Carbon (half burned) 4400 B. t. u. 

*Hydro-carbons 23500 B. t. u. 

Sulphur 4000 B. t. u. 

Every pound of coal contains these different substances 
and they must all be burned if all the heat is to be obtained. 
Carbon and sulphur which are solids and cannot get away 
are easy to burn if enough air is supplied. The hydro-carbons 
in the form of gas have a high ignition temperature and are 
likely to fly off up the chimney unburned in the smoke unless 
special care is taken. To make sure that there is air enough, 
more air than is theoretically necessary must be admitted to 
the furnace. Instead of twelve pounds of air per pound of 
coal, from eighteen to 24 pounds are usually used. These six 
to twelve pounds above what is theoretically necessary are 
known as "excess air." If too much air is allowed to enter 
the furnace it carries heat off up the stack and wastes it. The 
proper adjustment of the air is one of the fine points of good 
firing. 

Let us see now just what happens when coal is thrown 
into a furnace. As soon as the fresh coal strikes the hot fuel 
bed the latter is cooled down. The air coming in through 
the open furnace door also helps to lower the furnace tempera- 
ture. As the fresh coal heats up the gas begins to pass off, 



34 A Short Course for Janitor-Engineers 

starting at a temperature of about 220°, and coming off faster 
and faster as the coal heats up. This gas must be burned at 
once or not at all, for it is rushing off up the stack. To burn 
it, there must be air enough and the furnace must be hot 
enough. If the furnace has been cooled down too much by 
a heavy charge, the gas escapes unburned because it is not 
hot enough. If drafts are closed or not enough air can come 
through the fuel bed, the gas escapes unburned for lack of air. 
In either case, the dense black smoke is a signal that com- 
bustible gases are escaping and causing loss. It is easy to 
see that firing and handling a furnace require skill as well as 
muscle. Fuel and drafts must be handled together in order 
to secure the best results. Methods of firing which are 
simply the practical application of the principles of com- 
bustion will be taken up in the next chapter. 

Questions 

1. Mention the important things you would consider in selecting 
a coal from analyses furnished by the dealer. 

2. Under what conditions would you advise burning hard coal? 

3. What are the three conditions necessary for combustion? How 
much air is necessary to burn a pound of coal? 

' 4. Why is it desirable to admit more air to the furnace than is 
theoretically necessary to burn the coal? What is the effect of too much air? 

5. A coal contains 12622 B. t. u. per lb. A furnace and boiler make 
use of 63% of the heat units. How many units are available in the steam 
per lb. of coal? 

6. A floor space 15x20 feet is available for the storage of coal. Cal- 
culate dimensions of a bin to be placed on this floor large enough to hold 
40 tons. 

7. What is run-of-mine coal? What is lump coal? What is slack? 
What is steam coal? 

8. An engineer says his coal pile always starts to heat right under 
the hole where the coal is shoveled in. What is the reason for this and 
what would you do to prevent it? 

9. Does sulphur in coal have any harmful effect and if so, what is it? 

10. State briefly the differences between hard coal, soft coal, and 
coke, and the circumstances under which you would recommend their 
use as fuel. 



IV 
METHODS OF FIRING 

In the preceding chapter the principles of combustion 
were stated and explained. Proper firing is simply in accord- 
ance with these principles for the purpose of accomplishing 
two things: First, the elimination of smoke; second, greater 
economy in the use of coal. Elimination of smoke often means 
and usually does mean greater economy, but this is not al- 
ways the case. 

Smoke Prevention 

We sometimes hear the expression, "smoke consumption." 
There is no such thing as smoke consumption and the term 
should never be used. Perfect combustion means smoke pre- 
vention and to prevent smoke the fire should be managed so 
that combustion will be as complete and perfect as possible. 
The kerosene lamp used as an illustration will be useful here 
in showing the causes of smoke. Figs. 8a and 8b show two 
common ways of making a furnace or a lamp smoke. In Fig. 
8a the lamp smokes because it is turned too high. There is 
too much fuel for the air supply, therefore some of it gets 
away unconsumed in the form of gas and lampblack or soot. 

This represents the conditions in a furnace into which 
a very heavy charge of fuel has been thrown. The furnace 
conditions are really worse than those represented in the lamp 
because of the cooling effect of the fresh fuel. This does not 
occur in the lamp to any great extent. Fig. 8b represents the 
condition in a furnace when all drafts are closed with a heavy 
charge of fuel on the grates. The remedy in each case is to 
lessen the quantity of fuel or increase the air supply. The 
air supply of a lamp may be increased by increasing the height 
of the chimney. This may be done (for illustrative purposes) 
by inserting a pasteboard mailing tube or roll of paper in the 
chimney top. This will increase the draft and the lamp may 

35 




36 



Causes of Smoke 37 

be turned considerably higher without smoking. When the 
tube is removed the lamp at once begins to smoke again. 

Very short stacks and poor draft are often a cause of 
objectionable smoke. Over these conditions the fireman 
naturally has no control, unless the poor draft comes from 
leaky or clogged smoke passages. Fig. 8c shows a smoking 
lamp without a chimney. This smoke is due to the fact that 
the air, although it surrounds the wick and flame, does not 
have a chance to thoroughly mix with the fuel. For this 
reason particles of fuel escape unburned. When the chim- 
ney is in position, the air coming in through the holes under- 
neath mixes thoroughly with the fuel and burns it. This 
question of proper mixing of air and fuel is an important one 
in furnace construction. 

Fig. 8d shows another common method of producing 
smoke. A nail, or glass, or metal rod is held in the flame, 
cooling it down below the burning temperature. Smoke is 
immediately formed when combustion ceases or is hindered. 
This is what happens in a boiler with a small firebox in which 
the flames come in contact with the boiler tubes and shell 
before combustion is complete. The blazing gases are cooled 
off just as is the lamp flame, combustion ceases and a black 
cloud of smoke is the result. Soft coals containing a large 
amount of gas need a large combustion space so that com- 
bustion will be complete before the flaming gases strike the 
cold boiler surfaces. Fire brick arches are also used, which, 
by becoming white hot, aid in keeping the temperature up. 
To sum up the entire question of smoke prevention, it may be 
said that any fuel can be burned without objectionable smoke, 
provided it is mixed with the proper amount of air at the 
proper temperature. This, like many other things, is easier 
said than done. 




38 



Three Firing Methods 39 

Methods of Firing 

In a properly designed power plant using mechanical 
stokers, the prevention of smoke is easier than in the small 
hand-fired plant. Every fireman, however, should do his 
best to fire his furnace economically and with as little smoke 
as possible. It should be a matter of pride to say that black 
smoke seldom issues from the stack. In many settings smoke 
cannot be entirely prevented, due to faulty design, but much 
can be done toward lessening the smoke by proper methods of 
firing. There are in use three general methods: 

1. Spreading method. 

2. Alternate method. 

3. Coking method. 

When firing by the spreading method, the fireman spreads 
the coal as evenly as possible over the entire surface of the 
fuel bed. This is a common and satisfactory method for firing 
hard coal. It is not a satisfactory method for firing soft coal 
unless very small amounts are fired at one time. If the fresh 
coal in large quantities is spread evenly over the entire fuel 
bed, the temperature of the furnace is lowered considerably. 
The gases at once begin to pass off from the coal, due to the 
heat of the fuel bed below. As the furnace temperature is low 
over its entire surface the gases fail to ignite and pass off up 
the chimney unburned. The covering of the entire fuel bed 
also prevents the free passage of air through it at the very time 
when the greatest amount of air is necessary to mix with and 
burn the gases. See Figs. 10 and 11. Letting air in over the 
fire aids somewhat, but this cannot produce complete com- 
bustion if the temperature is too low. Hard coal can be 
fired successfully by the spreading method with little smoke 
because there is so little gas in it and it distills off so slowly 
that the incoming air can mix with and burn it satisfactorily. 

In firing by the alternate method the fireman spreads 
coal on one side of the furnace, leaving the other side as a 



40 A Short Course for Janitor-Engineers 

bed of fresh red coal, through which the air can pass freely. 
After the side just fired has become well ignited and red, a 
charge is fired on the other side. This process is continued 
and at no time is the entire fuel bed covered with fresh coal. 
The reason for this method is easy to see. The gases distilled 
off from the fresh charge are mixed with the hot air coming 
through the red coals on the other side and thus are consumed. 
The temperature of the furnace also is not lowered so much 
as it would be by covering the fuel bed entirely. See Fig. 13. 
A janitor very often says that, due to duties other than firing, 
he must be absent from the fire room often for quite a length 
of time. For this reason he must fire large charges and cannot 
give the fire the attention required by the alternate method. 
For this reason the third method, the coking method, is best 
adapted for firing furnaces in school buildings where the 
janitor cannot give undivided attention to the furnace. 

In firing by the coking method the coal is fired in quite 
a large charge right in front of the dead plates and allowed to 
coke or free itself of gas. The gas passing off must go back 
over the red hot fuel bed before it can get out of the furnace, 
and in so doing is burned. After the gas has distilled, the 
charge is shoved back bodily to the rear of the furnace, 
making the front of the fuel bed slightly lower than the rear 
and a fresh charge is again fired in front. This method is 
sometimes combined with the alternate method with good 
results in large furnaces. A janitor firing by this method can 
fire comparatively large charges with fair economy and a 
minimum of smoke. To produce the least smoke and best 
economy the coal should be fired in very small charges and 
by the alternate or spreading method. Fig. 12 shows the ap- 
pearance of a furnace fired by the coking method. Be care- 
ful that bare spots and holes do not form at the rear of the 
grate. 



Essentials of Good Fire 41 

Keeping a Good Fire 

A good fire in a furnace is light, bright and level. See 
Fig. 17. A light fire means a thin fire. A soft coal fuel bed 
should be from 4" to 10" thick for the best results, the heavier 
fires naturally are necessary in cold weather. The reason for 
a thin fire is to allow free passage of the air through the fuel 
bed and a proper mingling with the fuel. A thick fuel bed, 
like a blanket, prevents the passage of air unless the draft is 
very strong. A thin fire properly cared for makes steam easier 
and with less coal than a fire which is too thick. A bright fire 
means one which is red all through. A dull fire is clogged 
with clinkers and ash and cannot burn well. See Fig. 15. 
A thick fire is often a dull fire. A level fire is one which is the 
same thickness over the entire grate. If there are holes in 
the fire or bare spots on the grate the air rushes through them 
in much larger quantities than is necessary for combustion and 
carries heat off up the chimney and wastes it. Fig. 14 
shows the effect of holes in the fire. Bare spots are very 
likely to occur at the rear or sides of the grate. In filling up 
large holes do not use fresh coal, level the surface of the bed 
and fill the holes with red coals before firing a fresh charge. 
Remember that thick spots are points where the coal for some 
reason does not burn and should therefore be leveled off. It 
is often possible to prevent the formation of holes by firing 
the coal carefully each time, so as to fill up the thin places. 
By so doing the necessity of raking over the hot coals and 
stirring the fire is avoided. 

Special Methods and Appliances 

Hard coal needs a strong draft under it and no air over 
the fire. Soft coal, due to the combustible gases, needs a draft 
over the fire. Simply to let in air over the fire is not always 
enough. To be effective this air must be thoroughly mixed 
with the gases. When unobstructed the air and gases tend 




42 



Control of Draft 43 

to flow in parallel streams rather than to mix, as shown in 
Fig. 9c. Fire brick piers in the combustion space, on the bridge 
wall or beyond it, and wing walls and deflection arches are 
often installed to force the mixing of these streams of air and 
gas. Steam is sometimes forced in over the fire in a small, 
thin stream. This breaks up the currents of air and gas and 
causes better mixing. These steam jets as they are called 
are most effective when air is admitted around them instead 
of altogether through the firing door. In this way the steam 
jet acts as an air injector as well as a mixer. The velocity of 
the steam, not its quantity, is what counts. Air, not steam, 
supports combustion. 

If no steam jets are available, air should be admitted 
over the fire through the dampers in the firing door for a short 
time, say two to five minutes, after firing a fresh charge. 
Sometimes it is a good plan even to leave the firing door 
slightly open for a short time. To leave either door or drafts 
open after the gases have passed off wastes fuel by cooling 
the furnace and sending hot air up the stack. 

To control the draft under the grates use the stack 
damper rather than the ash pit doors. One reason is because 
it shuts off the draft through all openings, ash pit doors, leaks 
and firing doors and another reason is because it allows the 
cool air to circulate freely under the grates, thus preventing 
overheating and warping of the grate bars and the clinkering 
of the coal. To regulate the draft properly, the stack damper 
should be within easy reach or have a chain attached. See 
Fig. 18. There should also be in every fire-room a draft 
gauge, in such a position that it can be seen and the damper 
operated from the same spot. Fig. 18 shows a common form 
of draft gauge. It is simply a "U" shaped glass tube, f" 
or 5-16" diameter, filled with water attached to a graduated 
scale. Sixteenths of an inch are fine enough. The gauge is 
connected with the combustion chamber by a piece of \" 
iron pipe and a piece of rubber tubing. The draft gauge 



44 



A Short Course for Janitor-Engineers 



damper shoft 



Tf 




- 1- weight 



f/re door ( 



\£drafr gouge 



Draft Gauge .Show- 
ing i Draft 



Fi&ib 



Draft Gouge and Damper 
Connection 



shows the difference between the pressure of the gases in the 
setting and the air outside measured by the difference in 
height of the liquid in the two columns of the gauge. This 
difference is expressed in inches of water and we say the draft 
is \" of water or §" of water. 

After you have become familiar with the gauge you can 
tell what is happening in the furnace by looking at the gauge. 
If the draft over the fire is low when the damper is open wide, 
it means holes in the fire. If the draft is very high it means 
dense clinker or ashes on the grates. The average draft in the 
breeching in plants with 100 to 150 foot stacks is f" of water. 



The draft over the fire varies from V 



tor 



or more. 



Preventing Clinkers 45 

Clinkers 

Every fireman dreads clinkers, and for good reasons, and 
seeks to prevent them. As in other cases, to find the remedy 
we must know the cause. Clinker is simply melted ash, 
hence, if we can keep the ash from melting in the furnace, we 
can prevent clinker. The temperature at which ash will 
melt depends on two things, the chemical composition of the 
ash and the conditions under which it is melted. The most 
common causes of clinkers are the following: 

1. A thick fire. 

2. Stirring fire too much. 

3. Slacky coal. 

4. Closed ash pit doors. 

5. Fire in the ash pit. 

Thick fires cause clinker by making it necessary to send 
a large amount of the air for combustion over, rather than 
through, the fire. In this way the ashes in lower layers of the 
fuel bed and on the grate bars become overheated. By stirring 
the fire the ashes on the grates are brought up into the hot zone 
of the fire and melted. Slacky coal sometimes makes a crust 
or blanket over the top of the fuel, thus stopping the passage 
of air in the same way as a fuel bed which is too thick. Closed 
ash pit doors and fire in the ash pit cause overheating of the 
grates and ashes above them. The remedies for clinkers are 
clearly indicated by stating the causes. Above all things do 
not allow blazing ashes and coals to accumulate in the ash pit. 
See Fig. 16. It is a good plan to keep water in the ash pit 
because of its cooling effect and because it extinguishes the 
hot coals which drop through the grates. 

It is also stated on good authority that a little lime mixed 
with clinkering coal will make the clinkers easier to break up. 

Banking Fires 

To keep the fire over night in a heating plant the fire 
may be banked at the side, front or rear of the furnace. The 



46 A Short Course for Janitor-Engineers 

purpose of banking is to keep the fire burning slowly so as to 
have the means of making a quick, hot fire in the morning. 
In banking at the rear, the grates should have a little ashes 
left on them in front so that when the coal is raked toward 
the front in the morning the fine pieces will not drop through. 

The same precautions should be observed when banking 
the fire at the side or in front. Some firemen find it better to 
bank on the side because the fire can be turned over and spread 
in the morning with less loss of fuel through the grates than 
when the banking is done at the front or rear. To keep the 
fire over night it is not wise to close the stack damper tightly. 
Gas may accumulate and cause an explosion. 

In buildings heated by warm air furnaces it is often 
customary to let the fires die out at night, especially in locali- 
ties where woodworking plants provide an abundant and 
cheap supply of kindling. 

Questions 

1. Explain the difference in the methods of firing hard and soft coal. 

2. Describe fully your method of taking care of the ash pits and 
grates. 

3. Under what circumstances would you open the firing door to 
govern the draft? 

4. Would you use ash pit doors or the stack damper to regulate 
draft? Explain reason for your opinion. 

5. Under what circumstances would you wet coal before firing? 

6. A fireman claims that his coal clinkers badly. In examining his 
fire, state some things you would look for and some questions you would 
ask about his method of firing. 

7. Explain your method of banking a fire. 

8. Explain your method of cleaning a fire. 

9. A fireman says that he is troubled with lack of draft. State 
several common causes for this condition and what you would recom- 
mend in each case. 



THE HEATING PLANT 

The most important part of a heating system is the boiler. 
It needs careful, intelligent attention, not only for the sake 
of economy, but for the sake of the safety of the occupants of 
the building in which it is located. Even a low pressure boiler 
may explode with disastrous results. The following is a good 
set of rules for operating low pressure heating boilers: 

1. Blow out the water column and gauge glass and try 
gauge cock before starting fire in the morning. Do this 
several times a day. 

2. Try safety valve and if found out of order, report it. 

3. If sediment or sludge gathers in the boiler, blow the 
boilers through the bottom blow-off. Open the blow-off 
valves slowly and carefully, leaving them open three or four 
seconds, and close in the same way. Do not jerk the valves 
or open them suddenly. 

4. When shutting off steam lines, shut the return valves 
first, then close the steam valves. There may be check valves 
in the line, but do not depend on them. The reason for this 
rule is that if the steam valve is closed first, the condensing 
steam causing a vacuum will draw the water out of the boiler 
into the piping and radiators. 

5. Clean the flues with a good scraper at least every 
second day. 

6. If damper regulators are used, shut them off at 
night. 

7. Shut off the water glass at night. 

8. When cutting in a new boiler on a battery have the 
pressure the same on all boilers and then open the main stop 
valve very slowly. 

47 



48 A Short Course for Janitor-Engineers 

Washing Boilers 

Before washing a boiler be sure to let it cool down for 
at least 24 hours. Let the water run out through the 
blow-off valve. Remove the handhole and manhole plates 
both at bottom and top of the boiler. Scrape out all loose 
scale and sediment in the bottom of the shell and starting 
at the top wash down with a hose and nozzle under good 
pressure. Wash the bottom of the shell thoroughly. Remove 
plugs from water column connection and bottom blow-off 
connection and wash the pipes out thoroughly with a good 
pressure. 

Boiling Out 

Sometimes a boiler, especially a new boiler, will foam 
because the grease, oil and foreign matter have not been 
thoroughly blown out of the system before starting. When 
a boiler foams the water level bobs up and down in the gauge 
glass, making it impossible to tell where the true water level 
is. If a surface blow-off or skimmer is attached to the boiler 
the floating grease and oil may be removed through it. Grease 
and oil cannot be blown out satisfactorily through the bot- 
tom blow-off. One thing to be done is to cool the boiler off 
and wash it out thoroughly. This may have to be done 
several times before all the grease is removed. The trouble 
with this method is that as the water settles down the grease 
clings to the side of the boiler and does not wash out easily. 
A more satisfactory method of cleaning the boiler is the fol- 
lowing: 

Fill the boiler full of water and remove the safety valve. 
Connect on a piece of pipe leading off to the floor drain. Put 
a valve on the end of the pipe so that a little pressure may be 
created by throttling. Start a slow fire and make the water 
boil rapidly, the grease and dirt rising to the top will be 
thrown out through the pipe in gulps. Keep the boiler full 
and continue boiling until the grease and dirt cease to spit out 



Remedies for Boiler Scale 49 

through the valve. When the boiler is clean it may boil quite 
hard and no water will come out through the pipe even when 
it is very nearly full. 

Scale and Its Removal 

Boilers in which the same water is used over and over 
again give but little trouble with scale. In a boiler in which 
large quantities of fresh water are used, scale may give some 
trouble. The safest and surest way to avoid scale is to remove 
the scale forming ingredients before the water enters the 
boiler. This cannot always be done and hence we have need 
for various boiler compounds. In many cases the proper com- 
pound can be determined upon only after the water has been 
analyzed by a competent chemist. There are, however, two 
or three remedies with which every fireman should be familiar. 
Soda ash is the most common remedy. It is used and is ef- 
fective for a number of the most common scale troubles. Its 
action is to change the hard scale into a soft and easily re- 
movable scale. Caustic soda is also used, but is not recom- 
mended for general use except under the direction of some one 
who understands its properties. It costs more than soda ash, 
is a poison, has a corrosive action on the skin and causes vio- 
lent inflammation if it gets into one's eyes. 

Kerosene is another common remedy. It may be intro- 
duced drop by drop in some sort of sight feed apparatus or 
put in in small quantities some other way at frequent inter- 
vals. It does not have any chemical effect on the scale, but 
seems to loosen it and make it easier to remove. If the 
boiler is badly scaled up, kerosene may have to be sprayed in. 
To apply the kerosene properly empty the boiler while still 
warm and allow the scale to dry out. Then spray the kero- 
sene thoroughly over the scale and let it stand and soak in 
for six or eight hours. The scale will then be loosened suf- 
ficiently to be knocked off with a hammer. After knocking 
as much as possible clean the scale off thoroughly, otherwise 



50 A Short Course for J anitor-Engincers 

pieces may continue to flake off after the boiler goes into service 
and settling down on the heating surfaces make trouble. Be 
very careful never to take a torch into a boiler treated with 
kerosene until it has been thoroughly washed and aired out. 
Kerosene and air form a highly inflammable and explosive 
gas. The boiler should not be entered with a light, or even 
with a well protected electric light, without thorough airing 
for the fumes may suffocate or at least overpower a man. 

Laying Up a Boiler. 

When a boiler is to be put out of service for some time, 
it should be emptied of water and thoroughly cleaned inside 
and out. Soot and ashes should be most carefully scraped and 
brushed from flues, tubes and shell and all ashes and dust 
removed from the ash pit. The interior of the boiler should 
be thoroughly cleaned out and aired. Manhole and hand- 
hole plates and all brass plugs should be removed so that there 
will be a free circulation of air, and the safety valve should be 
lifted from its seat. Some firemen build a small fire to dry 
out the boiler. This is not a good plan, as the boiler may 
get quite hot and be seriously injured. A small kerosene stove, 
if one is available, may be used for drying out. To keep mois- 
ture from gathering, put two or three shovelfuls of unslaked 
lime in a box in the boiler and on the grates. If the cellar is 
damp, swab the fire tubes with oil on a rag and paint the 
exposed surfaces of the boiler in the same way. Be sure that 
all water connections are shut off tight. 

Heating Systems 

Steam heating systems are the most common in school 
and other public buildings. Hot water is used to some ex- 
tent and warm air is adapted to dwelling houses and the 
smaller public buildings. Several new terms will be used in 
describing steam and hot water systems and in order to have 
them understood they will be defined at the outset. 



Heating Plant Definitions 51 

Mains — Mains, as the name implies, are the main pipes 
leading from the boiler to the vertical pipes or risers. 

Risers — Risers are the vertical pipes from which the 
connections to the radiators are taken. These mains and 
risers are often called supply mains and risers to distinguish 
them from the return system. 

Returns — Returns is the general name given to all 
piping used to carry condensed steam from the steam mains 
back to the boiler. 

Radiator Runouts — Radiator runouts are the horizontal 
pipes connecting the radiators to the supply and return risers. 

Pitch — The pitch of a pipe is its slant or inclination from 
the horizontal. 

Relief or Drip — A relief or drip pipe is a small pipe 
connecting the steam to the return system or to a drain for 
the purpose of draining the pipe of condensed water. 

Water Line — The water line is the height at which water 
stands in the return pipes. This is higher than the water 
line in the boiler, but in a well designed system should not 
be more than 12" to 20" higher. 

Wet Return — A wet return is return pipe below the 
water level of the boiler. 

Dry Return — A dry return is a return above the water 
level of the boiler. A dry return carries both water and steam. 

Trap— A trap is an appliance placed between the steam 
and return system which allows water or air or both to be 
carried to the return, but prevents the steam from entering. 

Direct Radiation — Direct radiation is the name given 
to radiators placed in a room for the purpose of heating the 
air in the room over and over again. 

Indirect Radiation — Indirect radiation is the name 
given to radiators placed in ducts over which air passes on 
its way to rooms to be heated. 

Direct Indirect Radiation — Direct indirect radiation 
is the name given to radiators through which some outdoor 



52 A Short Course for Janitor-Engineers 

air passes coming through a special inlet in the wall. Part of 
the radiator heats directly and part indirectly, hence, the 
name. Many of these same terms apply to hot water as well 
as steam. Supply mains in a hot water system are known as 
"flow mains" and the returns as "return mains." 

Steam Heating Systems. 

Steam heating systems may be gravity systems, that is, 
systems in which the water returns to the boiler by gravity, 
or they may be pump return systems in which the water is 
pumped back into the boiler. Gravity systems are again sub- 
divided into one pipe, two pipe and combination systems 
and the overhead distribution system. In the one-pipe system 
a single pipe suffices to carry the steam and return the water 
of condensation. In the two-pipe system the supply and 
return systems are entirely separate. In the combination 
system the radiators and risers are connected on the one- 
pipe system and the mains on a two-pipe system. This is a 
simple and satisfactory method for ordinary buildings. In 
the overhead distribution system a vertical steam main is 
run to the attic or top story and vertical risers carry the 
steam down through the building. Hot water piping systems 
are similar to steam systems and will not be separately de- 
scribed. 

The greatest difficulty experienced both with steam and 
hot water systems is the stoppage of circulation by air. The 
removal of air is accomplished in several ways. The simplest 
method is to force the air out by steam or water pressure. 
As air is lighter than water the air valve is at the top of a hot 
water radiator. Since steam is lighter than air the air valve 
should be at the bottom of a steam radiator, but to avoid 
flooding it is placed about two-thirds the height of the radiator 
from the floor. 

Air valves may be closed by hand or may be made to 
close automatically against the steam. In hot water systems 



Steam Heating Systems 53 

the air valve is usually opened and closed by hand by means 
of a key. 

Forcing the air out by steam pressure is not always 
satisfactory, especially in large systems, hence we have the 
vacuum systems in which the air is removed by a steam ejector 
or by a pump, and the vapor systems in which the system is 
filled with steam and then automatically sealed by traps. 
The condensing steam causes a vacuum. In the vacuum 
systems the pressure is always less than atmospheric and con- 
sequently the temperature is less than 212°. In the vapor 
systems the pressure is usually atmospheric or a few ounces 
above and the temperature consequently is 212° or slightly 
higher. The advantages of vapor and vacuum systems are: 
positive removal of air and condensation; little or no danger 
from frost or leaks; rapidity of circulation and consequent 
rapid heating even in long runs of piping; small pipes and hence 
low cost of installation. 

In the vacuum and vapor systems some form of automatic 
valve is placed at the end of each radiator, which allows 
water and air to pass readily, but closes against steam. There 
are two types of these valves: the thermostatic and the float 
valve. In the thermostatic valve the heat of the steam 
expands a piece of metal to close the valve or evaporates a 
liquid inside of a sealed receptacle, which by its expansion 
closes the valve. In either case the heat, by means of ex- 
pansion, causes the valve to act. 

Float valves have a float which lifts the valve from its 
seat when water accumulates and allows the water to flow 
into the return. An auxiliary passage is provided for the air. 
Dirt is the great enemy of valves and traps and to keep a 
system working perfectly, dirt and grease must be kept 
out of it. 

Water hammer or pounding in the radiators is very an- 
noying to the occupants of a room, hence every janitor should 
do all in his power to prevent it. Water hammer is caused by 



54 



A Short Course for Janitor-Engineers 




One cause of pounding 

A radiator tilted the urong 
way. 

rig 19 




How a portial/y closed valve 
>5 tops arcu/ation of steam 



water in the system coming in contact with steam, hence, 
to prevent it, avoid water pockets. One of the most common 
causes of water hammer is the gathering of water above a 
leaky or partially closed radiator valve. For this reason 
radiator valves on a single-pipe or combination system should 
never be partially closed because this prevents the escape of 
the water from the radiator run-out. See Fig. 20. 

Sometimes a radiator with a single connection settles at 
the end farthest from the connection. Water gathering at the 
low point is almost sure to cause hammering. To remedy 
the difficulty raise the low end of the radiator so that it can 
drain. See Fig. 19. Water is sometimes forced up into 
radiators from the returns due to clogged valves or pipes or 
because the returns are too small for the radiation. If water 
backs up in this manner the return valves and piping should 



Placing Radiators 55 

be examined. Long wall coils must be carefully drained and 
pitched evenly or water pockets will form. 

In systems in which the heating coils are controlled by 
thermostats and diaphragm valves the pressure should not 
be run up too high in order to force steam through and heat 
rapidty. A pressure of more than ten pounds distorts the 
ordinary diaphragm valve and prevents its working easily. 
Five pounds should be sufficient to operate such a system. 
Too high pressure will also cause water hammer, due to the 
fact that considerable water is trapped in the radiator above 
the valves. 

One very important point to be kept in mind about re- 
turn piping is that it may contain a large amount of water, 
in some cases as much or more than the boiler. A second 
very important point is that no water can return to the boiler 
in a gravity system unless the water in the returns stands at 
least as high as the water level in the boiler. If the returns 
have been drained for any reason, say to prevent freezing, 
great care must be exercised in opening them to see that the 
water in the boiler is maintained at the proper level. The 
returns must be filled before any water returns to the boiler 
from the system. If the water in the boiler is evaporated to 
fill the returns without supplying fresh water, low water and 
a burned or cracked boiler will result. 

Direct and Indirect Systems 

In a direct or direct indirect system the radiators should 
be under a window or along the coldest side of a room. When 
radiators are so placed the best circulation of air is secured. 
In the indirect heating system (radiators below the floor and 
air passing over) the registers should be on the inner or un- 
exposed wall of the room, a system just opposite to that em- 
ployed in direct heating. Indirect radiators should always be 
connected on the two-pipe system because there is so much 
condensation to be carried off. In operating an indirect or 



56 A Short Course for Janitor-Engineers 

direct-indirect system the dampers letting in the outdoor air 
should be closed at night in order to avoid waste of fuel in 
heating unnecessary fresh air, and also to avoid freezing. 

Circulation of air is absolutely necessary for proper heat- 
ing. Air must come into the room and go out or must move 
about in the room. A radiator will not heat if the air does not 
circulate through it. Books or shelves should not be placed 
on radiators as they prevent the rise of air between the sec- 
tions and thus impede circulation. Opening a window for a 
time even on a cold morning will often start circulation and 
cause a room to heat up more quickly than if the window is 
kept closed. Circulation may often be established through 
doors opening into other rooms or halls. In a church or other 
building heated at comparatively long intervals a sluggish 
circulation may be started by placing an electric fan near a 
radiator and blowing air over it. 

Warm Air Systems 

So far nothing has been said in regard to warm air heating 
systems. Firing methods, as described, apply to all heating 
systems. Due to the fact that a warm air system warms a 
building rapidly, fires are often allowed to go out during the 
night and are rekindled in the morning. This is desirable in 
mild weather, especially if a good supply of kindling is avail- 
able, as in a town where there are large woodworking industries. 

In operating a warm air system care must be exercised 
to see that the air has a chance both to enter and leave the 
room. Air cannot be forced into a room by a furnace if it 
cannot get out at the same time. Outdoor and indoor air 
circulation systems will be discussed under ventilation. By 
regulating the volume dampers in the basement leaders, the 
flow of air to different rooms can be controlled. Direction of 
wind makes a great deal of difference and this must be watched 
and the system operated accordingly. Long pipes, poorly in- 
sulated pipes, pipes with many turns and bends and pipes with 



Questions and Problems 57 

but little pitch are the most difficult to send the warm air 
through. These must be watched and sometimes started by- 
closing off other pipes until a circulation is established and the 
pipe warmed up. A warm air system must never be entirely 
closed either with the volume dampers or the floor registers. 
This prevents air circulation over the heating surfaces and 
the furnace will crack and burn out exactly as an empty boiler 
burns out if exposed to a hot fire. For school buildings in 
the daytime the air supply should come from outside. At 
night means should be provided for the circulation of the in- 
side air after the building has been well aired out. This saves 
fuel. 

Questions 

1. Having a boiler with full steam pressure on, explain how you 
would empty it and prepare to inspect it. 

2. Explain your method of laying up a boiler for the summer season. 
What is the object of lifting the safety valve from its seat? 

3. What effect does oil have if it gets into a boiler? 

4. What do you look for in case a radiator pounds? 

5. What is the advantage of admitting steam at the top of the 
radiator on one side and taking the condensation out on the other side 
at the bottom, as in a vapor system? 

6. Explain the reason for using a steam trap and how it works. 
How does an air valve work? What is the chief cause of trouble in steam 
traps? 

7. Engineer A says it is a good plan to drain the returns of a steam 
heating system so as to form a partial vacuum in the coils, thereby giving 
a quicker circulation of steam. Is he right? 

8. If a leak started in a pipe on the third floor of a building heated 
by hot water, what would you do? 

9. What is the object of having a check valve on the return line of 
a steam heating system? 

10. When shutting off a steam system, would you shut the return 
or supply valve first, and why? 

1 1 . Engineer A says there is no use in having a governor to control 



58 A Short Course for Janitor-Engineers 

the vacuum pump on the return line, it ought to run all the time anyhow 
in order to keep up the vacuum and take out the water. Is he right? 

12. A schoolhouse is heated by a gravity single line system. The 
teacher persists in partially closing the radiator valves to regulate the 
heat. She says in other schoolhouses they regulate the heat that way and 
she doesn't see why it cannot always be done. Explain the difficulty. 



VI. 
GOOD AND BAD AIR 

The janitor or engineer is the custodian of the health and 
safety of the occupants of his building. It is not enough to 
keep the rooms at a proper temperature, fresh, pure air, 
properly conditioned is absolutely necessary to health. Its 
importance is illustrated by the fact that a man can live three 
weeks without food, three days without water and three 
minutes without air. Prof. S. H. Woodbridge, of Boston, 
says "death rates have been reduced by the introduction of 
efficient ventilating systems in children's hospitals from 
50 per cent to 5 per cent; in surgical wards of general hospitals 
from 44 to 13 per cent; in army hospitals from 23 to 6 per 
cent. For young and growing persons such as those in our 
schools, fresh air is especially necessary. Bad air causes 
headache, lassitude and mental weariness. It is also both a 
direct and indirect cause of tuberculosis, diphtheria, measles, 
scarlet fever and other diseases. Germs of disease may be 
directly communicated from one person to another in the 
foul air or his vitality may be so lowered by breathing foul 
air that when exposed to disease elsewhere he is unable to 
resist it. Sore throats, colds and various lung diseases are 
the most common bad air diseases. The human body con- 
tinually gives off moisture and odors and sometimes disease 
germs. If air in a room remains still and stagnant a thin 
blanket of warm, moist air forms around the body and pro- 
duces a feeling of stickiness and discomfort. This blanket 
must be swept away by currents of fresh air if we are to be 
kept comfortable. Anyone who has been confined in a close, 
crowded room knows what discomfort bad air causes. 

Before we can explain the difference between good air 

59 



60 A Short Course for Janitor-Engineers 

and bad air we must know something about the composition 
of air. Air is a mixture chiefly of nitrogen and oxygen, 4-5 
being nitrogen and 1-5 oxygen. Oxygen is the vital part 
which we breathe into our lungs. Nitrogen dilutes the oxy- 
gen. Carbonic acid gas, or C0 2 , as it is called, is present in 
small quantities in good, pure air, usually measured as so 
many parts in 10,000. Good, pure air contains 3 to 4 parts 
in 10,000. Water vapor also exists in the air in varying quanti- 
ties, depending on the temperature, the wind, and whether 
bodies of water are near. Dust and other impurities are also 
present in varying quantities, depending on the location. 

Just at present engineers are somewhat uncertain as to 
just what "bad air" is. Some standard is necessary. For 
many years the carbonic acid or C0 2 standard has been used. 
According to this standard, pure air contains 3 or 4 parts of 
C0 2 in 10,000. Air containing 4 to 8 parts in 10,000 is still 
good. Air containing more than 8 parts is not considered good 
air. This standard is not altogether satisfactory, but at 
present is the best we have. The amount of C0 2 present, how- 
ever, must not be considered a conclusive test of the purity or 
impurity of air. Other things affect it as we shall see. The 
question naturally arises as to where the C0 2 comes from. It 
comes from the breath and from the burning of various sub- 
stances in the air such as gas jets, lamps, candles, coal fires, 
wood fires, etc. Most of it, especially in school buildings, 
comes from the air breathed out by the occupants. If air con- 
taining four parts in 10,000 of C0 2 is breathed into the lungs 
it will contain about 400 parts in 10,000 when breathed out, 
or about 100 times as much. This air is totally unfit to be 
breathed again. Hence, large amounts of fresh air are neces- 
sary to keep the proportion of C0 2 as low as 6 to 8 parts in 10,- 
000. The amount of fresh air necessary may be calculated 
as follows: Suppose we desire to keep the C0 2 contents down 
to 6 cubic feet in 10,000 cubic feet, and suppose the fresh air 



Human Breathing Requirements 61 

• 6 4 



contains four cubic feet in 10,000 



10,000 10,000 



2 2 
cubic feet increase allowed. expressed as 



10,000 10,000 

a decimal is 0.0002. Every adult person gives off about 0.6 
cubic feet of C0 2 per hour, hence, the amount of air to be sup- 
plied per person is 0.6 -r- 0.0002 = 3,000 cubic feet per hour. If 
the proportion of C0 2 is raised to eight parts in 10,000 
this allows an increase of 0.0004 and the air necessary per 
person is 0.6-^0.0004 or 1,500 cubic feet per hour. At the pres- 
ent time not less than 30 cubic feet per minute per person, or 
1,800 cubic feet per hour are considered necessary for healthful 
conditions. Gas jets also vitiate the air in a room. One gas 
jet vitiates as much fresh air as 3 to 5 persons. Electric 
lights do not affect the air in this way. The American Society 
of Heating and Ventilating Engineers has for many years 
been studying the problem of maintaining conditions of health 
and comfort in various classes of buildings. The following 
recommendations are of particular interest to men in charge 
of buildings as indicating what these engineers consider to be 
minimum requirements for floor space, cubic contents, air 
supply and regulation and temperature: 

Space Per Occupant (Minimum Requirement) 

Schools and colleges — class, study, lecture and recita- 
tion rooms, floor area per occupant in square feet — 15. 

Schools and colleges — class, study, lecture and recita- 
tion rooms, cubic space per occupant (volume divided by 
number of persons) in cubic feet — 180. 

Primary schools — class and study rooms (pupils under 
8 years of age), floor area per occupant in square feet — 12.5. 



62 A Short Course for Janitor-Engineers 

Primary schools — class and study rooms (pupils under 8 
years of age), cubic space per occupant in cubic feet — 150. 

Theatres, auditoriums and court rooms — floor space per 
occupant in square feet — 90. 

Factories, manual training rooms and other work rooms — 
cubic space per occupant in cubic feet — 250. 

Minimum space conditions in all classes of buildings or 
rooms not tabulated shall be reasonable and practical and 
shall meet the approval of the Department of Health. 

Air Supply (Minimum Requirement) 

The supply of outdoor air for the following classes of 
rooms shall be positive and based on a minimum quantity of 
cubic feet per occupant per hour as tabulated: 

Class, study, lecture and recitation rooms in all schools 
and colleges, cubic feet per occupant per hour — 1,800. 

Theatres, court rooms and other auditoriums — 1,200. 

Factories, manual training rooms and other work rooms 
—1,500. 

All air supply for ventilation must be from an uncon- 
taminated source or air from which the dust or other impuri- 
ties shall be sufficiently removed by washing, or otherwise, 
subject to the approval of the Department of Health. 

Air Distribution 

The distribution and temperature of the air supply for 
ventilation shall be so arranged as to maintain the temperature 
requirement, without uncomfortable drafts, or any direct 
draft lower than 60° F., and as a test of proper supply and 
distribution, it shall be required that the C0 2 content shall 
not at any time exceed 10 parts in each 10,000 parts of air, 
based upon tests of air samples taken in a zone from 3 to 6 
feet^above the floor line in any part of the occupied spaces. 
This requirement may be modified by the Department of 



Tijyes of Ventilating Systems 63 

Health or other properly constituted authority as applying 
to breweries, water charging rooms or other rooms where 
carbon dioxide is liberated in manufacturing processes. 

Note: While carbon dioxide in the air, in reasonable 
quantities, is not considered injurious to health, its presence 
in occupied rooms is an accurate measure of the air supply 
and distribution if no other source of carbon dioxide is present 
except the occupants of the room. 

Temperatures 

The temperature of the air in occupied rooms in all 
classes of buildings, during the periods of occupancy, shall 
be not less than 60° F., nor more than 72° F., except when 
the outside temperature is sufficiently high that artificial 
heating in the building is not required. This requirement 
shall not apply to foundries, boiler or engine rooms, or special 
rooms in which other temperatures are required or advisable 
as approved by the Department of Health. 

Systems of Ventilation 

There are in general use three methods of ventilation. 

1. Natural methods, in which open doors, windows, 
flues or chimneys are used to introduce the fresh air and 
remove the foul air. 

2. Ventilation by aspiration or systems in which the 
natural draft of a chimney or flue is increased by heaters or 
heating coils. 

3. Forced ventilation (sometimes called mechanical 
ventilation) or a system in which a fan is used to supply air 
or remove it from a room or both. 

The natural method of ventilation is the simplest of all 
and also the most unreliable. The amount of air coming in 
through windows, doors and cracks is extremely variable and 
hard to control. It has been shown by tests that the air 



64 A Short Course for J anitor-Engineers 

leakage into and out of a room of average construction amounts 
to one to three changes of the entire contents per hour. In 
practice it is customary to count on at least one change per 
hour when considering the matter of ventilation. For dwelling 
houses with direct steam or hot water heating, very fair ventila- 
tion may be obtained by this method under certain conditions. 
For example, a room 12'xl2'x8' contains 1,152 cubic feet. 
Allowing one and one-half changes of air per hour gives a 
supply of nearly 1,800 cubic feet, a fair amount for one person. 
Double windows, weather strips, storm doors, etc., restrict 
the leakage; hence, many houses are poorly ventilated in the 
winter time and we find the occupants suffering from colds 
and sore throats. Naturally, this method is not adapted to 
any building or room where there are a number of occupants. 
If fresh air and foul air ducts are provided, conditions are 
somewhat better, but any system which depends on the natural 
movement of air for circulation is uncertain and should not be 
depended upon where large amounts of fresh air are necessary. 
The aspiration method aids in removing the foul air 
from a room by warming the air in the foul air flue, thus 
creating the draft. Fresh air comes in as the foul air goes out 
through warm air registers, around direct and indirect radia- 
tors and through windows and doors. If the aspirating coils 
are supplied with steam or if the air is warmed by a separate 
heater, the operating cost of this system of ventilation is high 
because a large amount of heat is required to create a small 
air movement and the heat is lost. If the heat of the flue 
gases in a chimney is used to warm the air in the foul air flue 
the cost may be neglected, as this heat would be lost anyway. 
Even when supplied with heating coils a vent flue is not posi- 
tive in its action. When the wind blows in a certain direction 
there may be a draft down instead of up the flue. This is 
one objection to this method of ventilation, but the principal 
one is its lack of capacity, hence, it is suited only to rooms 
which have a small number of occupants for their size. 



Forced Ventilation 65 

Forced or mechanical ventilation is the method best 
suited for school buildings because the amount of air supplied 
is under control at all times and independent of wind or 
weather. There are two ways in which the air maybe supplied, 
the plenum method and the exhaust method. In the plenum 
method the air is forced into the room under a slight pres- 
sure. The foul air escapes through vent flues in the walls, 
being forced out by the incoming fresh air. In the exhaust 
method the foul air is sucked or drawn from the rooms by a 
fan. The fresh air rushes in to take the place of the foul air 
drawn out. In some cases a combination of these two systems 
is used, one fan drawing out the foul air and one fan forcing 
in the fresh air. This is known as the balanced system. 

In many cases the ventilation system also supplies the 
air for warming, as in the case of a warm air furnace or indirect 
radiation. The term "fan system" is applied to all systems 
in which air is supplied by a fan, the heating being done 
usually by steam, though in some cases the air is forced over 
the heating surfaces of a furnace. There are two kinds of 
fan systems in use, the direct and the indirect. In the in- 
direct system all the heating is done by steam coils or a warm 
air furnace near the fan, and the air for ventilation carries this 
heat to all parts of the building. 

The temperature of the air is regulated according to 
weather conditions by the steam coils or heating surfaces 
over which the air is passed. In the direct system, the air 
supplied by the fan is heated only to the room temperature 
of about 68°. The fan supplies air for ventilation only. 
The rooms are kept at proper temperature by radiators in- 
stalled in the rooms. 

Figure 21 is a diagram of an indirect fan system. The 
fresh air is drawn from outside through the window on the 
right. It first goes through a tempering coil where the tem- 
perature is raised to 60° or 70°. The temperature is con- 
trolled by the by-pass damper below the tempering coil. This 




INDIRECT F/1N SYSTEM 
Fg£l 




DIRECT INDIRECT F/IN SYSTEM. 
Fg.ZZ 



06 



Types of Fan Systems 67 

allows more or less of the air to pass directly to the fan without 
being heated. If necessary, steam may be shut off from some 
of the coils. After leaving the fan, part of the air is forced 
over more heating surface, which raises the temperature much 
higher. It then enters the large chamber at the left, known 
as the plenum chamber or plenum room, because the air is 
under a slight pressure here. The plenum chamber contains 
two compartments; one receiving all the air passing over 
the heating coils on the discharge side of the fan and the 
other receiving only the tempered air passing below the 
heating coils. From the plenum room ducts lead to the rooms 
to be heated. Mixing dampers allow hot air, tempered air or 
a mixture of both in varying proportions to be supplied to 
the different rooms. A mixing damper is so made that as one 
leaf leading to one compartment opens the other one closes. 
This admits a constant quantity of air, but controls the pro- 
portions of heated and tempered air. 

The heating coils on the discharge side of the fan are 
controlled by thermostats or hand valves. In mild weather 
a number of them can be shut off. As will be shown later, 
some provision should be made for moistening the air. Steam 
jets are satisfactory for this purpose, and are placed between 
the tempering coils and the fan. The foul air vent for the 
room is shown near the floor at the opposite end of the room 
from the warm air register. 

Figure 22 shows the direct-indirect fan' system. The room 
is heated by steam coils or radiators, the fan supplies air for 
ventilation only. The cold air from outside is heated to room 
temperature only by tempering coils. The by-pass damper 
allows more or less of it to pass over the heating coils in order 
to meet the requirements of varying outdoor temperature. 
The plenum room communicates directly with the ducts 
leading to different rooms. The dampers regulate the amount 
of air going to different rooms, but not its temperature. The 



68 



A Short Course for Janitor-Engineers 




Air 



Window open 
at bottom 



window 
board 




/4tr check for 

outside intake 

r7f.Z4 



check 



wire netting' 



Board to checA 
direct draft 
F7g.M 




foul o/r 
gang 

OUT 



Ar check for inside vent flue 

n g z5 



steam jets for moistening are also necessary and should be 
located as shown. 

Operation of Natural and Aspiration Systems 

Windows are an uncertain method of ventilation and the 
direction of the draft through them depends largely on the 
wind. In general, however, to ventilate a room and cool it, 
the windows should be opened at the top, because the warm 
air is at the top of the room. To get fresh air in where it can 
be breathed the windows should be opened at the bottom, if 
possible on opposite sides of the room, so as to get a current 
of air through the room. If windows are not placed on oppo- 
site sides of the room some windows should be open at the top 
and some at the bottom. To prevent drafts from striking 
occupants seated near a window a board may be placed as 



Natural Ventilation 69 

shown in Fig. 23. In some schools large screens of unbleached 
muslin have been made and inserted under the sash-like fly 
screens. These keep out dust and prevent draft and are 
said to give good ventilation. They are, however, likely to be- 
come dirty and unsightly in appearance. In cold weather it 
is a good plan to open a window at the bottom over a radiator 
if the air blows in. In this way the air is warmed somewhat 
before passing into the room. If, however, the air blows 
outward, heat will be wasted. It is not a good plan to open 
a window at top and bottom over a radiator because the air 
is likely to circulate in and out without passing into the 
room. Refer to Fig. 3. Care should be exercised in opening 
windows in toilet rooms. If the air blows in strongly, odors 
will be carried into the building. All rooms should be thor- 
oughly aired out several times a day. Doors and windows 
should all be opened, giving the fresh air currents a chance 
to sweep the foul air out. Foul air ducts are often located 
in a wardrobe or cloak room. When this is the case, be sure 
that overcoats and coats are not hung so as to cover them up. 
The surest way to avoid such a possibility is to remove all 
hooks from above the foul air register. 

In an aspiration or natural system there will sometimes 
be a strong back draft down the foul air flue on windy days. 
To prevent this from blowing back into the room, curtains 
or flaps can be installed as shown in Fig. 25. These close 
against the grating if air blows down the flue, but do not 
obstruct the outward passage of the air. These foul air ducts 
should be closed at night after the building has been thor- 
oughly aired. 

In case a building is heated with a furnace or by indirect 
radiation the cold air inlets should have doors opening in- 
ward which can be regulated with rope and pulley and held 
in any position. They should not flap up and down. At 
night these doors should be closed and the air of the building 
recirculated. During the day they should be regulated ac- 



70 A Short Course for Janitor-Engineers 

cording to varying conditions of wind and temperature. 
Nothing should interfere with opening the door to full ca- 
pacity when necessary. Cold air inlets and ducts should be 
kept as clean and free from dust as possible. Clean, pure 
air cannot come from a dirty, dusty, ill-smelling duct. A 
form of check for an outside air intake is shown in Fig. 24. 

The Operation of Fan Systems 

The fan system is most satisfactory to operate because 
the air supply is under control at all times. Foul air and 
fresh air inlets and ducts should receive the same care and 
attention as in the case of the natural and aspiration systems. 
In warming up the building air should be recirculated as ex- 
plained before. During the day all the air supply should 
come from the outside. Mixing dampers will need care and 
adjustment from time to time. Using a fan with a direct 
heating system will be found to economize steam in the 
radiators because the circulation of air equalizes the tem- 
perature at floor and ceiling. Without the fan the tempera- 
ture may be 10° to 20° higher at the ceiling. By starting the 
fan, a room temperature may be raised several degrees by 
circulating the air from ceiling to floor level without ad- 
ditional heat. In heating up an empty building in the morn- 
ing with a fan system the air in the building should be re- 
circulated so as to economize fuel. Outside fresh air is not 
necessary until the occupants arrive. 

To save fuel, cold outside air should be used sparingly 
whenever the rooms are empty. 

One great difficulty in operating a fan system satis- 
factorily is caused by opening windows in different parts of 
the building. Windows should be opened from time to time 
in order to flush the building out, but in order to interfere as 
little as possible with the fan system all windows should be 
opened at the same time. The following plan adopted in 
Chicago has been found to give good results: 



Handling a Ventilating System 7 1 

Directions to Janitors 

"The principals, with the co-operation of the teachers, will 
arrange for flushing the rooms with fresh air by the opening 
of windows and classroom doors throughout the building at 
practically the same moment, in order that advantage may 
be taken of the prevailing wind. The temperature of the rooms 
should not be allowed to fall below 55 degrees, Fah., and the 
responsibility for the habitable condition of the classrooms 
will be placed upon the respective teachers. In extremely 
cold weather the windows should be opened but slightly and 
careful attention given to prompt closing of same. Except 
where special permission is given by the Chief Engineer, win- 
dows are to be opened during these periods only: 

"Recess in morning session; close of morning session; re- 
cess in afternoon session. 

"Whenever the atmospheric conditions are such that the 
mechanical system of ventilation is closed down, the principal 
will be notified of same. It is suggested that the principals 
and engineers of buildings agree on a series of signals which 
may be given on the school gongs; such a system is now in 
operation in a number of buildings. 

"One ribbon §"xl4" will be placed over each heat inlet 
where practicable, and teachers are urged to communicate 
at once with the principal should this ribbon indicate a clos- 
ing down of the mechanical system at a time when it should 
be in operation. Windows and doors are to be opened as well 
as closed by the teachers." 



As has been said, there is some uncertainty in regard to 
the amount of fresh air necessary and the advisability of re- 
circulating washed air. The following conclusions of the 
Chicago Commission represents safe practice and are worthy 
of the attention of every janitor and engineer: 



72 A Short Course for J anitor -Engineers 

Conclusions of the Chicago Commission on Ventilation 

in Regard to the Heating and Ventilation 

of Schoolrooms 

Resolved, That either the plenum or vacuum principle 
is applicable to the ventilation of schoolrooms. 

Resolved, That in the artificial ventilation of a school 
room, the air inlets and outlets should be of such size, number 
and location as to insure equal distribution of air throughout 
the room. 

Resolved, That the maximum temperature for a school 
room, artificially heated, should not be more than 68 degrees F. 

Resolved, That in the present state of knowledge and 
practice the quantity of air supplied to schoolrooms for 
ventilation should not be less than 30 cubic feet per pupil 
per minute. 

Resolved, That both the design and location of the air 
intake for a school building should be such as to minimize 
the possibility of contaminating the air supply. 

Resolved, That efficient air cleaning devices are desirable 
in all ventilating installations where the air supply is liable 
to be contaminated by dust, or other objectionable matter. 

Resolved, That in the automatic control of temperature 
within a schoolroom, the thermostat should be so located as 
not to be influenced by wall chill. The thermostat should be 
so located as to be influenced by the average temperature of 
the room only. 

Resolved, That in mechanically ventilated school build- 
ings, it is desirable at stated periods to flush all the school 
rooms in the building with fresh air by means of open windows. 

Resolved, That careful consideration should be given to 
the sweeping and cleaning of the school room as affecting its 
ventilation. 



Questions on Ventilation 73 

Resolved, That the carbon dioxide content alone is not 
always an index of the contamination of air for ventilating 
purposes, within an enclosure. 

Questions 

1. A teacher says that the way to ventilate a room is to open all 
the windows at the top so that air will come in at some and go out at 
others. Is this correct? 

2. Would you prefer, when running a fan system, to have all the 
windows in the building opened at once for airing out and all closed at 
once or to have them opened a few at a time at intervals? 

3. In a certain school building in which there is a fan system of venti- 
lation and direct steam for heating, the teachers complain that soon after 
the fan is shut down there is a cold draft along the floor. What causes 
it and what remedy would you suggest? 

4. A building is dependent for ventilation on windows and doors. 
The teacher says she cannot open the windows on account of the cold 
draft on the pupils. How would you remedy the difficulty? 

5. In a building heated with a warm air system, the warm air goes 
out the cold air duct when the wind blows in a certain direction. Sug- 
gest a remedy. 

6. Engineer A says that a thermometer placed in moving air or a 
draft will show a lower temperature than when placed in the same air when 
still. He says moving air always feels cooler and is cooler than still air. 
Is he right? 

7. In school buildings provided with a fan system, the fresh air ducts 
are usually at the ceiling and the foul air ducts near the floor. In a kitchen 
or restaurant the foul air ducts are near the ceiling. Why? 

8. Explain the difference between the direct and indirect fan sys- 
tems and the advantages of each. 

9. In a certain school building in which air was washed and recircu- 
lated it was found that less steam was required to keep the building warm 
when the fan was running than when the fan was shut down. How do 
you account for this fact? 

10. Explain what you would do in shutting down the following sys- 
tems for the night in cold weather: (a) indirect fan system, (b) direct fan 
system, (c) direct and direct indirect steam radiation without fan. 



VII 
HUMIDITY 

Proper temperature and proper ventilation are neces- 
sary for the comfort and health of the occupants of a building 
or room, but they are not the only conditions necessary. 
Proper humidity or moisture in the air is just as important 
as proper temperature and ventilation. That air contains 
moisture, we know, for we can see it in the form of fog, rain 
or snow. Sometimes we cannot see it when it is in the form 
of water vapor or steam because steam is invisible. Ordi- 
narily we think of steam as being hot, but the invisible water 
vapor in the air is steam just as truly as the steam in a boiler, 
only it exists at a lower temperature. When the invisible 
vapor condenses we see it as water or ice, in the form of fog, 
rain, snow or the sweat on a pitcher or pump on a sultry sum- 
mer day or frost on our windows in winter. 

Air is like a sponge, for it will absorb and hold various 
amounts of water vapor, depending on its temperature, just 
as a sponge will absorb various amounts of water, depending 
on its size and texture. Warm air is like a large, soft sponge, 
which will hold a great deal of water. Cold air is like a small, 
hard sponge, which will not hold much water. In other words, 
the capacity of air for moisture increases as the temperature 
increases. This does not mean that warm air always contains 
more moisture than cold air any more than a large, soft sponge 
always contains more water than a small, hard sponge. Warm 
air will absorb and contain more moisture than cold air if 
the moisture is available. Naturally, more moisture is avail- 
able near the ocean or lakes than in inland districts; more in 
the valleys than on mountain tops, and more in the forests 
than on the open prairie or sandy deserts. 

Carrying the example of the sponge a little further, we 
know that to get the water out of it, we squeeze it. To get 

74 



Relative vs. Absolute Humidity 75 

the water out of air we do not squeeze it, but cool it and the 
vapor condenses to water. This is what happens when a 
warm, moist current of air is chilled by a cool breeze. Down 
comes the moisture in the form of rain. Drops gather on the 
side of a water pitcher or pump on a sultrv day because 
the air near the pitcher or pump is cooled and the water vapor 
condenses. If the temperature is below freezing, we get snow 
instead of rain and frost instead of water drops. The moisture 
in the air is called its humidity. The humidity may vary 
from the maximum amount of moisture which the air can 
contains at a given temperature down to almost nothing. 

When considering proper air conditioning, the important 
point to be noted is that it is not the actual amount of moisture 
present that determines whether the air feels dry or moist. 
It is the amount of moisture contained in the air compared to 
what the air could contain at that temperature, if it had all it 
could hold. Here again the sponge is a good illustration. We 
judge whether a sponge is wet or dry, not by the actual amount 
of water contained, but by the amount contained compared 
with what it could hold if saturated. The amount of moisture 
actually in air compared to what it could hold is called the 
relative humidity and is expressed in percentages. For in- 
stance, the relative humidity at a certain time may be given 
as 40%. This means that the air has in it 40% as much 
moisture as it could hold in a saturated condition at the same 
temperature. Weather reports give the relative humidity at 
different times of day on different days. The following are 
examples : 

Humidity at 12 M 70% 

Humidity at 4 P. M 40% 

Relative humidity tells us nothing directly as to the 
actual amount of water present in the atmosphere and, as 
has been said, this is not important for our comfort. The 
actual amount of water present in the air at any time is called 



76 A Short Course for Janitor-Engineers 

the absolute humidity and is sometimes given for scientific 
reasons. Humidity tables give the absolute humidity as so 
many grains per cubic foot. One grain is 1-7000 of a pound. 
For instance, air at 70° may contain 6 grains of moisture per 
cubic foot. It might contain 5 grains, 4 grains, 3 grains, or 
any quantity down to nothing. It could never contain more 
than 7.98 grains per cubic foot at 70° because that is all the 
air will hold at that temperature. It is then said to be satur- 
ated or to have a relative humidity of 100 per cent. Humidity 
tables may be found in scientific textbooks or in commercial 
catalogs such as that of the Carrier Air Conditioning Co., New 
York City, or the Buffalo Forge Co., Buffalo, New York. 

To show the variation in the capacity of air for moisture 
at different temperatures the following table is given. The 
weight of moisture contained is stated in pounds per 1,000 
cubic feet instead of grains in one cubic foot. Note that the 
amount of moisture stated is what the air contains in a satur- 
ated condition at the given temperature. 

Lbs. Water Vapor 

Temperature Contained in 1000 

of Air °F. Cubic Feet of Air 

0° 0.068 

12° 0.122 

22° 0.194 

32° 0.301 

40° 0.407 

50° 0.583 

60° 0.821 

70° 1.140 

This table clearly shows that warm air can hold much 
more moisture than cold air. The relative humidity may be 
determined, provided the temperature and moisture content 
are known. For instance, suppose the temperature is 60° 
and the moisture content 0.35 pounds per 1,000 cubic feet, 



Relation of Humidity to Temperature 11 

what is the relative humidity? Saturated air at 60° contains 
0.821 pounds in 1,000 cubic feet. Since this air contains only 

0.35 

0.35 pounds, the relative humidity is = 0.42 or 42%. 

0.821 

Another problem is to find the actual moisture content 
when the temperature and relative humidity are given. 
Suppose the temperature is 40° and the relative humidity 
60%, what is the absolute humidity? Saturated air at 40° 
contains 0.407 pounds per 1,000 cubic feet. With 60% 
humidity it contains 0.407X0.60 = 0.244 pounds per 1,000 
cubic feet. 

In the same way, the actual amount of moisture for any 
relative humidity can be calculated. Outdoor air in this sec- 
tion of the country has an average relative humidity of 70%. 
In dry desert regions the relative humidity may go down as 
low as 12% to 25%. 

We often hear the statement that heating air dries it 
out. This is not true. Air cannot be dried out by heating it 
like a sponge or a wet rag. The relative humidity is lowered 
when air is heated and this affects our health and comfort. 
Let us see how this happens. Suppose that outdoor air, 
having a temperature of 32° and a relative humidity of 70%, 
is taken into a building and heated to 70°. The actual amount 
of moisture in the air is not changed, but the relative humidity 
drops to 17%. The reason for this is as follows: Saturated 
air at 32° contains .301 pounds of moisture per 1,000 cubic 
feet. At 70% humidity, as stated, it contains 0.301X70 = 
0.210 pounds per 1,000 cubic feet. When the air is heated the 
1,000 cubic feet expand to 1,077 cubic feet. Hence, in every 

1,000 

1,000 cubic feet of air there are X0.210 pounds of 

1,077 



78 



A Short Course for Janitor-Engineers 



Air 
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Depre^o/on, or Difference be/ween Dry and 
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Fig. 26 



moisture = 0.195 pounds. Air at 70° when saturated contains 
1.140 pounds in 1,000 cubic feet. This heated air contains 



0.195 



only 0.195 pounds. The relative humidity is 



= 17%. 



1.140 



The air has not dried out, but the relative humidity is 
greatly decreased due to the fact that the warm air could 
contain so much more moisture than it actually does contain. 
It makes no difference whether the air is heated by steam, hot 
water or a furnace, the effect is the same. In making ordi- 
nary, quick calculations it is not necessary to allow for the 
expansion of the air, as was done in the preceding example. 



Effects of Humidity 



79 



Simply take the moisture content of the air with the humidity 
given and divide it by the moisture content of saturated 
air at room temperature. In the above example by this 



0.210 



method we would have 



= 18% instead of 17% when 



1.140 



accurately calculated. If the outdoor air were very cold the 
difference would be greater. 

Effects of High and Low Humidity 

From the foregoing discussion it is clear that the air in 
artificially heated rooms must be much drier than outdoor 
air. In most cases the indoor air is too dry for health and com- 
fort in the winter time. It shrivels the skin, dries out furniture, 
kills plants and allows various bad air diseases to develop, 
due to its effect on the glands of the throat. These little 
glands under normal conditions discharge a fluid which kills 
disease germs. If the air is too dry, they discharge water 
only in order to keep the throat moist. If germs are breathed 
in they can grow and develop because the germicidal fluid is 
not present. Many persons when compelled to breathe very 



lemoerma \\ 
Heater u j! 



/ 



/iir 
Washer 




r : ~> 



To c/osi 

rooms 



Fig. 27. Side View of Air Washer and Fan. 



80 A Short Course for Janitor-Engineers 

dry air are immediately troubled with a hacking cough and 
a sore throat, no doubt due to these disease germs, which 
under normal conditions would be killed. Dry air in a room 
also causes the occupants to feel nervous and feverish. 

Another effect of dry air is to make us feel chilly even a t 
a temperature of 70°. To understand this we must bear i n 
mind the fact that evaporation of moisture cools the surface 
from which evaporation takes place. Alcohol, ether, gasoline 
or any volatile liquid feels cool when poured upon the hands 
because it evaporates so easily. Perspiration evaporating 
from the body cools it in the same way and the drier the air 
the more rapid the evaporation and the greater the cooling 
effect. If the air is very dry, our bodies are cooled so much 
that we feel chilly. It is for this reason that a room at 68° 
properly humidified feels more comfortable and just as warm 
as a room at 72° containing very dry air. If more moisture is 
present, the temperature may drop to 65° without causing 
chilliness. Too much moisture is uncomfortable as well as 
too little, because if there is too much moisture in the air, 
evaporation cannot take place rapidly enough to keep the 
body cool. For this reason a sultry, muggy day is very op- 
pressive. As has been said, the average outdoor humidity is 
70%. If, however, we attempted to make the air in our 
houses in winter time as moist as this, drops of water would 
gather on the walls and the windows would be completely 
covered with a thick coating of frost. On mild days this would 
melt and run down over walls and window sills. Humidity in 
dwelling houses and schoolhouses should run from 30% 
to 50% and not fall below 30%. 

How Humidity is Measured 

In order to keep the humidity of a building or room at 
the proper degree, there must be some means of measuring it. 
For this purpose three different instruments are used: the 



Measuring Humidity 



81 




SUA/G RSrCHROMETCR 
F/g. £8 



hygrodeik, the hygrometer, and the sling psychrometer. 
Fig. 28. Of all these the sling psychrometer is the most satis- 
factory and accurate. Its action is very simple and easy to 
understand. It consists of two thermometers known as the 
wet bulb and dry bulb thermometers. The dry bulb ther- 
mometer is an ordinary thermometer such as is used for taking 
temperatures. The wet bulb thermometer, as its name in- 
dicates, has a piece of muslin or other porous material wrapped 
around the bulb and saturated with water. When the instru- 
ment is used it is whirled about with a rapid, even motion, 
thus causing a strong current of air to pass over the bulbs. 
We have already said that evaporation cools the surface from 
which it takes place. The water evaporating from the muslin 
surrounding the wet bulb cools it and causes the temperature 
to fall below that shown by the dry bulb thermometer. The 
drier the air, the more rapid will be the evaporation and the 
faster and farther the wet bulb thermometer will fall. It 
will finally come to rest at a point determined by the tempera- 
ture of the room and the moisture present in the air. The 
difference between the readings of the wet and dry bulb ther- 
mometers indicates a certain percentage of humidity. This 
may be caclulated, but the practical way is to read it from a 
table like the one shown as Fig. 26. For instance, suppose 
the dry bulb thermometer read 72° and the wet bulb 60°. 
To find the relative humidity we first subtract 60° from 72°. 
This gives 12° as the depression or difference between the wet 



82 A Short Course for Janitor-Engineers 

and dry bulb thermometers. Now look down the column 
headed "air temperature" and find 72°. Run across to the 
right to the column headed 12. Opposite 72 and under 12 we 
find 49. This means that the relative humidity is 49%. 
As another example, take a dry bulb temperature of 68° 
and wet bulb temperature of 54°. The difference is 14°. 
Opposite 68 and under 14 we find 39. The relative humidity 
under these conditions is 39%. 

A sling psychrometer as described is not always avail- 
able. Very good results may be obtained with a 25-cent 
dairy thermometer in the following manner: Tie the ther- 
mometer securely to a string, 12 or 14 inches long, so that it 
may be swung like the psychrometer. See that the bulb is 
perfectly dry and take the room temperature at some point 
away from the wall and out of reach of warm or cold drafts. 
Note this temperature. Wrap a small piece of rag about the 
bulb and fasten with thread or string and saturate the rag 
with water. Take hold of the end of the string and walk about 
the room swinging the thermometer vigorously at the end of 
the string. (Be careful not to hit the wall or desks.) After 
swinging for 15 or 20 seconds, take a reading. Swing and read 
again. Do this until the temperature becomes stationary. 
The last reading is the wet bulb temperature. Subtract this 
from the dry bulb or room temperature previously noted 
and find the humidity from the table as before. 

Supplying Moisture to the Air 

As has been explained, moisture must be supplied to 
rooms artificially heated. Otherwise the relative humidity 
is too low for health and comfort. Let us see just how much 
moisture is necessary. Suppose we have a schoolhouse con- 
taining 200 pupils for whom there is an air supply of 30 cubic 
feet per minute per pupil. This means 30X200 = 6,000 cubic 
feet per minute and 60X6,000 = 360,000 cubic feet per hour. 



Putting Moisture into Air 83 

Suppose the outdoor air has a temperature of 32° and a re- 
lative humidity of 70%. How much moisture must be added 
if the humidity in the room is to be 40% with a temperature 
of 70°? From the table on page 76 we find that air at 32° 
and saturated contains 0.301 pounds of moisture in 1,000 
cubic feet. If the relative humidity is 70%, there are 0.301 X 
0.70 = 0.210 pounds of moisture in 1,000 cubic feet. This air 
is brought into the building and heated to 70°. Air at 70° 
and saturated contains 1.14 pounds of moisture in 1,000 cubic 
feet. With 50% humidity it must contain 0.57 pounds. Since 
the incoming air contains 0.21 pounds, the amount to be added 
to every 1,000 cubic feet is 0.57-0.21=0.36 pounds. The 
amount of moisture to be supplied per minute for 6,000 cubic 
feet of air is 6X0.36 = 2.16 pounds. The amount required per 
hour is 2.16X60= 129.6 pounds, or about 15| gallons. In this 
calculation no allowance has been made for the expansion of 
the air when heated. The result shows clearly that a consid- 
erable quantity of moisture must be added to fresh outdoor 
air in order to keep the humidity at the proper point after 
heating to room temperature. 

This moisture can best be introduced in the form of steam. 
For this purpose take a piece of pipe five or six feet long and 
drill in it a number of \" holes 6 inches apart. Plug up or put 
a cap on the outer end and put a valve on the other end. 
Connect this with the boiler and allow steam to blow into the 
air supplied to the building. In case there is no direct air 
supply into which this moisture can be introduced, a small 
attachment known as an air moistener may be screwed on 
the radiators. This allows steam to escape quietly into the 
room. This can be used only on pressure systems. Air 
washers and humidifiers are now being used quite commonly. 
The incoming air is washed by passing through a spray or 
sheet of water and is humidified at the same time. In many 
cases the humidity and temperature are automatically con- 
trolled. Fig. 27 shows an air washer. 



84 A Short Course for Janitor-Engineers 

In case a building is furnace heated and no steam is avail- 
able, moisture must be introduced in the form of water. Some 
furnaces are supplied with water pans and if they are kept 
hot enough to evaporate the water rapidly, sufficient moisture 
can be supplied. If these do not supply sufficient moisture, 
water may be introduced in the form of a spray in the warm 
air spaces. In this case a drip pan will be necessary to catch 
the excess water. 



Conclusions of the Chicago Commission on Ventilation 

on the Subject of Humidity and Proper 

Temperatures 

Resolved, That the relative humidity of a schoolroom, 
artificially heated, should not fall below 40 per cent. 

Resolved, That the temperature of a schoolroom should 
be kept as low as the comfort of its occupants will permit; 
and that the temperature may be kept down by increasing 
the relative humidity. 

Resolved, That in the proper ventilation of a school build- 
ing in cold weather, it is necessary to provide means for 
humidifying the air introduced into the buildings. (See note.) 

Resolved, That a constant temperature and a constant 
relative humidity are not conducive to the highest degree of 
comfort in a schoolroom. 

Resolved, That in the production of comfort for the occu- 
pants of a schoolroom, the maximum temperature should be 
associated with a minimum relative humidity, and the mini- 
mum temperature should be associated with a maximum re- 
lative humidity. 

Resolved, That in a school building artificially ventilated 
and heated, the comfort zone should be established in order 
that the engineer may properly operate the heating and venti- 
lating system. 



Putting Moisture into Air 85 

Note: Relative humidity may be increased in a school 
room by means of properly muffled jets of steam introduced 
into the plenum or fan chambers from the boiler supply. 

Questions 

1. Enginner A says that adding moisture to the air is not necessary 
because heating does not take any moisture out. There is just as much 
moisture indoors as outdoors, even in the winter time, and hence condi- 
tions are satisfactory. Do you agree? If not, explain how you differ. 

2. Engineer B says that heating air "dries it out" and hence moisture 
must be added to replace that which is "dried out." Is he right? If not, 
explain. 

3. Engineer C says that it is impossible for us to feel warmer in a 
humidified atmosphere, for everyone knows that we feel the cold more in 
a damp climate than in a dry one. Is he right, and if not, how do you ac- 
count for the fact which he states? 

4. Professor B says that a dry atmosphere is good for pupils. If 
it isn't, why do people with lung trouble seek a dry western climate? 
Do you agree with him? 

5. Engineer A says that with steam and warm air heat, we may 
need moisture, but not if hot water heat is used, because hot water heat is 
more moist. Is he right? 

6. In a certain schoolhouse no frost gathers on the windows even 
in the coldest weather. What would you say about the condition of the air? 

7. In a certain room the dry bulb temperature is 72° and the wet 
bulb 54 °. What is the percentage of humidity? 

8. On a summer day the temperature registered 70 ° and the humidity 
was given as 87%. How many pounds of moisture were there in one 
thousand cubic feet of air? 

9. Explain why moisture in the air contributes to our health and 
comfort. 

10. Engineer A says that in testing for humidity that we should whirl 
the dry bulb thermometer about on the string and if we do the temperature 
will fall 5 or 6 degrees. Is he right? 



VIII 
SWEEPING, CLEANING AND SANITATION 

Sweeping and Cleaning 

Cleanliness is the great protection against disease. Sta- 
tistics show that tuberculosis and pneumonia are the two 
greatest causes of death in this country. The germs of both 
diseases are "air borne," that is, they are carried by the small 
particles of dust and dirt floating in the air and are breathed 
into the throat or lodge in the mouth and nose. Germs of 
measles, scarlet fever, diphtheria and other less important 
diseases are similarly carried. The janitor can do a great deal 
to eliminate these diseases by removing in a harmless way the 
dust and dirt which accumulate each day — dust and dirt 
which may many times be laden with disease germs. 

Sweeping 

Sweeping a room with a dry brush merely collects and 
removes the heavy dirt and stirs up the lighter dust to settle 
again in the same room. If a feather duster is used, the light 
dust is merely stirred up without removing it and it settles 
a second time. Dry sweeping in some states is forbidden 
by law, but where vacuum cleaning sj^stems are not installed 
the janitor is dependent on some form of sweeping and scrub- 
bing to keep his building clean. To keep down dust while 
sweeping, some kind of sweeping compound should be used. 
Snow was probably the first kind of sweeping compound em- 
ployed. Now there are various kinds obtainable, consisting 
chiefly of sawdust, sand, or pulverized woody fibre moistened 
with water or oil. This compound is sprinkled on the floor 
and, when pushed along with the broom, gathers and holds 
the dust. It is most useful on large, smooth, unobstructed 

86 



Sweeping, Cleaning and Sanitation 87 

floors. In schoolrooms where the furniture is attached to the 
floor, the particles lodge in and around the legs of desks and 
accumulate in corners which are hard to reach. Commercial 
sweeping compounds are sometimes expensive. Home made 
ones are less expensive and often just as satisfactory. Saw- 
dust moistened with water or kerosene is the simplest and 
least expensive. Another way to make a sweeping compound 
is to dissolve a teacupful of boiled linseed oil in a gallon of 
gasoline and pour it onto all the sawdust that can absorb it. 
The gasoline evaporates at once and merely serves to spread 
the oil through the sawdust. Another compound is made 
as follows: 1 lb. sawdust, 1 lb. fine sand, \ pint water, \ 
pint kerosene. The sand and sawdust are mixed and the water 
and kerosene added. It is a good plan to wet the compounds 
with a liquid disinfectant diluted with water according to 
the strength of the disinfectant used, as an average, perhaps 
two or three tablespoonsful to a quart of water. 

Instead of sweeping compounds, floor dressings are some- 
times used composed of oil which will not dry hard upon the 
floor. Some claim that this oil imparts sufficient moisture to 
the dust to permit sweeping without raising a dust. The 
method has met with some success in schoolhouse work. One 
objection to it is, that the oil and dirt gradually accumulate 
and make a dirty floor. Another objection is that the dust, 
which may contain germs, is retained in the room and not 
removed from dangerous nearness to pupils. Another at- 
tempt to keep down dust has been to use oil brushes. These 
brushes differ from ordinary floor brushes in that they have on 
the top a pan or reservoir which keeps the bristles moist with 
kerosene or some other inexpensive oil. These brushes must 
be used carefully in order to avoid applying an unnecessary 
amount of oil to the floors, causing streaks. With proper use 
they are effective and are a long step in a hygienic direction. 



88 A Short Course for Janitor-Engineers 

Special Methods of Cleaning 

Marble and tile floors should be mopped with hot suds 
and scrubbed with a soft hair brush to give a polish. A cement 
floor requires a hard brush, hot water and solvene powder or 
some other form of washing powder. For rough floors of hard 
or soft wood, use a scrubbing brush with soap and water and 
mop thoroughly. For varnished floors, use cold water and 
soap. Some varnishes will stand hot water. 

The following mixture used as a sweeping compound 
is said to take off stickiness and stains. Mix thoroughly a 
pint of soft soap with three quarts of water. Pour this mix- 
ture into two-thirds of a bucket of sweeping compound and 
stir until thoroughly absorbed. Give the floor a hard sweep- 
ing with this, using a soft bristle brush. If the floor is only 
slightly dirty it should be swept with a soft hair brush and 
dusted with an oiled mop. 

Painted walls and floors should be cleaned with hot water 
and soap. 

Toilet seats should be flushed thoroughly and washed 
with hot soda or soapy water, using a soft bristle brush. 

To take off stains of iron or other discoloration, muriatic 
acid is effective. This acid will not corrode porcelain or a 
vitrified surface. It must never be used even in a diluted 
form on any enameled surface. 

For the walls and floors of shower baths, use a hard 
brush and hot soapy suds. 

To clean dirty wash bowls use a cloth wet with gasoline. 

To clean brass, use two ounces of oxalic acid mixed with 
one quart of water. Rub thoroughly and remove with a 
damp cloth. Soap and water are as good as anything for 
cleaning ordinary door knobs. 

Clean windows are important because of their effect on 
the lighting. Experiments have shown that clean windows 
increase the light from 6% to 33%, depending on how dirty 



Cleaning Methods 89 

they are in the first place. For cleaning either dry or liquid 
cleaners are good. Dry cleaners have one disadvantge, namely 
that when they are rubbed off, the dust flies about and settles 
on other things. Liquid cleaners consist of clear water or 
water mixed with washing soda, ammonia, kerosene or alcohol. 
Kerosene and alcohol may be used alone. The chief precau- 
tion necessary in using liquid cleaners is not to get so much 
liquid on the glass that it will run and cause streaks. To polish 
a window after dirt has been removed a chamois skin is best, 
as it leaves no lint. If kerosene and alcohol are used, un- 
diluted, they must be kept away from the framework of the 
sash, for they will soften paint and varnish. For this very 
reason, alcohol or turpentine is good to remove paint spots. 
Some recommend scraping with a dull knife or coin. If the 
spot must be removed by rubbing, a small cloth bag about 
the size of a 48-caliber bullet filled with powdered pumice 
stone is more effective and easier to use than the knife or coin. 

To polish varnished woodwork make a mixture of one- 
third turpentine and two-thirds boiled oil. Soak a cloth in 
this and wring out very dry. Rub the surface to be polished 
thoroughly and hard. 

An ordinary public building should be swept at least once 
a day. If dry sweeping must be done, all windows should be 
opened if the weather will permit, so as to carry off as much 
of the dust as possible and to give the room a thorough airing. 
For ordinary sweeping, a soft, mixed bristle brush of the 16" 
size is best. The handle should be frequently changed from 
one side to the other so as to wear the bristles evenly. To 
clean it, comb it out with a cleaner like a currycomb and wash 
with lukewarm (not hot) water. Do not wet the glue at the 
upper end of the bristles. After cleaning stand the brush 
upright on the handle where it will dry as quickly as possible. 
All cloths and brushes used in water should be well cleaned 
after using and quickly dried. Treated in this way, they will 
last much longer than if left neglected and dirty. For cleaning 



90 A Short Course for Janitor-Engineers 

radiators, special soft bristle brushes are made. For sweeping 
cobwebs from walls and ceilings, use a long handled, soft 
bristle brush with bushy corners. To sweep dust from a 
smooth or papered wall, use a cloth on a straw broom. For 
a rough finish wall, use a straw broom without cloth and sweep 
vigorously. For dust rags, cheesecloth is the best material. 
When used, it should be lightly sprayed with linseed or kero- 
sene oil. This keeps dust from rising and flying about the 
room. Dust cloths should be thoroughly washed with hot 
water at frequent intervals in order to kill all disease germs. 
Be very careful not to use too much oil or desks and tables 
will be sticky. 

Sanitation 

To prevent the spread of disease where large numbers of 
children or adults are gathered, more than sweeping, dusting 
and scrubbing is necessary. Disease germs must be killed, 
for they cannot all be removed because they gather on walls 
and floors or are carried about from one place to another on 
the person or clothing or are blown about in the floating dust 
in spite of all we can do. These germs cannot live at all 
temperatures, but unfortunately the temperature of our 
dwelling houses and buildings is well suited for their multiplica- 
tion and growth. A very low temperature renders some germs 
inactive and may kill some. Heat will kill them, applied by 
baking, boiling or steaming. It is, however, manifestly im- 
possible to bake, boil or steam an entire building, hence some 
other means of killing germs must be resorted to. This is 
called disinfecting. A disinfectant is a germ killer or germi- 
cide. Disinfectants used may be gases, liquids or solids in 
the form of powders. 

One of the commonest gases for disinfecting is formed by 
burning sulphur and is known as sulphur dioxide. This is an 
excellent disinfectant and works best in moist, steamy air. 
Sulphur for this purpose can be best obtained in the form of a 



Health and Cleanliness 91 

sulphur candle. This is lighted like an ordinary candle and left 
burning in the room. Sulphur dioxide gas is not very penetrat- 
ing and hence is not good for fumigating mattresses and bed- 
ding in order to kill bedbugs and other vermin. A large quan- 
tity of sulphur must be burned to make the process thorough 
because the gas must be very strong in order to kill the germs 
and they must remain in it for some time. It does not kill 
quickly. One disadvantage in using sulphur dioxide is the fact 
that it attacks metals. Polished brass, silver, nickel or 
aluminum turn black when exposed to it. It also has a bleach- 
ing action on colors. 

Formaldehyde gas is another common disinfectant. This 
is not poisonous, strictly speaking, and does not attack metals 
or bleach out colors. It has a very irritating effect on the eyes, 
nose and throat. The gas is formed by heating a liquid solu- 
tion of formaldehyde in water, thus driving off the gas. Some- 
times the solution is simply sprayed about the room on floors 
and walls and allowed to evaporate. This is not very effective. 
Hydrocyanic gas (one of the most deadly poisons known) 
is sometimes used for fumigating. This gas will, in a short 
time, kill every living thing with which it comes in contact. 
It is, therefore, especially valuable in killing vermin. One or 
two good breaths of it are fatal to a human being. It should 
never be used except under the direction of a medical expert 
or health officer. When disinfecting a room by gas, be sure 
that all openings, such as doors, windows and air registers, 
are tightly closed. Drawers and cases should be opened and 
books, clothing, curtains and portieres spread out so that the 
gas can get all through them. After disinfecting, open and 
thoroughly air out the room. 

Carbolic acid, sometimes called "phenol," is the most 
common and one of the oldest liquid disinfectants used. It 
is a deadly poision and hence must be handled with great 
caution. There are many commercial germicides sold under 
different names. These are generally marked with what is 



92 A Short Course for Janitor-Engineers 

known as the "phenol coefficient." This is a number which 
compares their strength with that of carbolic acid. For 
instance, if a germicide has a phenol coefficient of ten it means 
that it is ten times as strong as carbolic acid. Some states re- 
quire that all germicides be marked in this way. Bichloride 
of mercury, commonly called corrosive sublimate, is another 
deadly poison often used in solution as a liquid disinfectant. 

Solid disinfectants like choloride of lime can only be 
sprinkled about and hence are not as effective as liquids and 
gases. Whitewash has a slight disinfecting action and is good 
for cellar and basement walls, where it will help the lighting as 
well as disinfect. 

Health authorities usually require that school buildings 
be disinfected whenever there is an epidemic of any infectious 
or contagious disease. If any pupil has been found to have a 
disease, the room should be disinfected at once. Owing to the 
prevalence of chicken pox, measles, scarlet fever, whooping 
cough, etc., school buildings and rooms should be systematical- 
ly disinfected at regular and frequent intervals, and be kept 
thoroughly clean and sanitary at all times. Disease germs 
thrive in dirty quarters. This is so important that many states 
prescribe that floors, desks, wainscoting, stair rails, door knobs, 
window sills and blackboards be wiped at intervals with 
a disinfecting solution. One state at least requires this to be 
done daily. 

Toilet rooms are the most difficult parts of a building to 
keep clean and sanitary. The general principles of plumbing 
should be understood by every man in charge of public 
buildings. These can only be suggested here. Fixtures 
are arranged with water sealed traps so that no gases can get 
back from the pipes to the rooms. Piping systems are 
"vented," that is, open at the roof, and have an air inlet lo- 
cated on the ground near the outlet of the system from the 
building. This allows free circulation of air through the 
pipes and removes all gases that form. It is very important 



Disinfectants and Their Use 93 

that the system be absolutely sealed by traps at every 
possible outlet into the building. Toilet fixtures should be 
cleaned daily with some disinfecting solution that will kill 
any and all germs. The disinfectant can be placed in the soap 
and water used for cleansing. Deodorants are sometimes used. 
A deodorant simply absorbs or covers up objectionable odors. 
It should not be confused with a disinfectant. A deodorant 
does not necessarily destroy germs and hence is not always 
a preventive of disease. 



RULES AND REGULATIONS 

FOR CLEANING AND CARE OF SCHOOL 
BUILDINGS AND GROUNDS 

(Used by courtesy of Geo. F. Womrath, Business Supt. 
of School Board, Minneapolis, Minn.) 

1. Each head janitor shall be responsible for the cleanly 
condition of his building, and he must be observant of dirt, 
dust and bad odors and see that same are removed without 
having special attention constantly called thereto. 

2. In order that the school building may be properly 
cleaned, janitors are to be permitted by the principal to begin 
their schoolroom cleaning not later than twenty minutes after 
the close of the afternoon session. 

3. Under no circumstances is there to be any sweeping 
done while the schools are in session with exception of corri- 
dors and stairs, except by permission of the principal of the 
school. 

4. Under no circumstances shall coal oil or kerosene be 
used for cleaning purposes. 

5. When no night school is held, each school building 
must be carefully and thoroughly swept each school day, 
the work to be commenced twenty minutes after the close of 
the last session and to include the entire building, together 
with outside closets, if any. 

6. In buildings where night school is held, the janitor 
shall pick up after the close of the day session all waste paper 
and rubbish from the floors and furniture of the rooms which 
are used for night school, and shall in other ways put the 
school in a neat and clean condition before the opening of the 
night session, and shall have the building properly lighted and 
heated one-half hour before the opening of the night session. 

7. In buildings where evening school sessions are held, 
all classrooms and other floor space used for night school 

94 



Rules for Building Care 95 

must be thoroughly swept, commencing fifteen minutes after 
the close of night session. 

8. Assembly halls must be kept in as neat condition as 
classrooms. 

9. All woodwork, moldings, window sills, wainscoting, 
handrails, radiators, pianos, pictures, casts, shelves, chalk 
troughs, principals' desks, teachers' tables, pupils' seats and 
desks, chairs, furniture and apparatus of every description 
must be thoroughly dusted each school day. 

10. Every school building must be thoroughly cleaned 
three times each year as follows: 

During the summer, Christmas and Easter vacations, the 
engineers and janitors shall thoroughly brush all the walls, 
ceilings and window shades of their respective buildings be- 
fore proceeding to wash the woodwork, which shall include 
oil painted walls, dadoes, baseboards, wainscoting, doors, 
frames, sash and all painted and varnished woodwork. They 
shall thoroughly wash with water the glass in all windows, 
transoms and furniture, and dust all picture moulding and the 
fronts and backs of all pictures. The floors of all entries, 
halls, passages, stairways, corridors, and all rooms occupied 
for school purposes and stair landings shall then first be well 
scrubbed with scrub brushes and then mopped. 

11. Chairs and desks shall be washed three times a year 
and at same time the general cleaning is done. 

12. Chairs and desks which have been occupied by pupils 
who have contracted a contagious disease shall at once be 
thoroughly washed with a disinfectant to be furnished by the 
Supply Department. 

13. Kindergarten rooms must be thoroughly swept and 
dusted after the morning session as well as after the afternoon 
session. 

14. Kindergarten floors must be scrubbed at least once 
each week and must be wiped off with a damp mop or rag each 
morning before school opens. 



96 A Short Course for Janitor-Engineers 

15. Manual training rooms shall be thoroughly swept 
and dusted each day after the rooms are used and all shavings, 
sawdust and rubbish must be removed. 

16. The cooking room, including pantry and dining 
room, shall be scrubbed once every week and shall be swept 
and dusted, and the garbage bucket emptied and cleaned 
each day that the room is used. 

17. Extra precautions shall be taken in cleaning around 
the radiators, and to see that rags, paper or any other material 
of an inflammable nature does not come in contact with the 
radiators by being on or behind them. 

18. In buildings heated by hot air. furnaces, and where 
floor registers are used, the register boxes must be cleaned at 
least once a week, and oftener if necessary. 

19. Doors and door-knobs of schoolrooms and hand- 
rails and banisters of stairs shall be washed at least twice each 
month with a disinfectant to be furnished by the Supply 
Department. 

20. Janitors shall keep gas and electric fixtures clean, 
removing rust and dirt from interior of all X-Ray reflectors 
at least once each month. 

21. All sidewalks, pavements and yards shall be swept 
as often as is required to keep them in good condition and at 
least twice each week. 

22. All outhouses, areas, light-courts, sidewalks, gutters, 
playgrounds, grass plats, lawns, store rooms, boiler rooms, 
cellars, attics, roofs, etc., shall be kept in a neat and tidy con- 
dition free from all rubbish, stones, litter, pieces of paper and 
other waste matter of every description, and clean and in 
order at all times, and the janitor is to allow no accumulation 
of paper, wood, ashes or refuse of any kind therein or thereon, 
and a tour of inspection for the observance of these conditions 
shall be made at least once every day. 

23. The urinal troughs and the floors around them shall 
be flushed with a hose after every recess period. 



Rules for Building Core 97 

24. All closet seats shall be kept dry and bowls flushed 
during school sessions. 

25. The urinal troughs, seats of the closets, fixtures 
and floors shall be washed and disinfected every day after 
school sessions, and tanks in connection with water closets 
must be kept free from mud and other sediment. 

26. The water closet bowls and urinals and all par- 
titions to urinals and backs of same shall be cleaned at least 
once each week with a disinfectant to be furnished by the 
Supply Department. 

27. At all times a sufficient supply of toilet paper shall 
be kept in each toilet room and towels wherever there is a 
lavatory. 

28. All toilet paper and towel racks out of order must 
be reported at once. 

29. The water and gas shall be turned off at the supply 
mains at the close of school each day and on again just before 
the opening of school in the morning. Every precaution shall 
be taken in cold weather to prevent all pipes and other ap- 
paratus from freezing and to see that all plumbing fixtures 
are drained during freezing weather. All damage resulting 
from freezing of plumbing, pipes, apparatus or other fix- 
tures will be charged to the janitor. 

30. In extremely cold weather, after the water has been 
shut off from the building, drain the toilet and urinal tanks, 
open all faucets, and then fill toilet bowls and traps on fixtures 
with a solution of salt water. 

31. All slop sinks, wash bowls and other fixtures through- 
out the building shall be cleaned every school day. 

32. Janitors shall not clean nor allow any of their as- 
sistants^to^clean the windows of their school buildings on the 
outside while standing on the outside window sills or ledges 
of the school buildings without the use of a window platform 
or harness furnished for that purpose. 

33. After snowstorms, a path is to be cleared on all 



98 A Short Course for Janitor-Engineers 

walks and steps in and about the school premises before 8 
A. M. so as to provide access to the several entrances to the 
buildings and to outhouses. 

34. All snow and ice must be removed from the steps, 
fire escapes, entrances and inside and outside walks of the 
school premises before 12 o'clock noon of the same day that 
the storm occurs. 

35. Janitors shall sprinkle sand or ashes or salt upon 
sidewalks when they are in a slippery condition; a supply of 
sand, ashes or salt for this purpose to be kept on hand. 

36. Janitors shall keep fire escapes clear and clean at all 
times. 

37. During the winter months the boiler room, engine 
room and inside of all fresh air shafts are to be whitewashed. 

38. Special attention is to be given to the flow of water 
in urinals, drinking fountains, etc., and all leaks promptly 
stopped, and the water for urinals, drinking fountains, etc., 
turned off as soon as school is dismissed. 

39. The electric current used for lighting, power or 
stereopticon shall be shut off from the building at the service 
switch each night before leaving the building. 



THE JANITOR'S CATECHISM 

1. Do you practice damp sweeping? 

2. Do you use a moist or oiled cloth for wiping up dust? 
.3. Do you ever use a feather duster? 

4. Do you use a disinfectant on the floors? 

5. Do you clean the desks with a disinfectant? 

6. Do you disinfect the school books when necessary? 

7. Is your ventilating system in good working order? 

8. Are some of the windows always opened if the fan is not running? 

9. If there is no mechanical system of ventilation, are some of the 
windows always open at top and bottom? 

10. Are window boards placed under the lower sash to prevent draft? 

11. Are all windows thrown open at recess? 

12. Have the tops of the desks been redressed within two years? 

13. If any room is heated by a stove is there a jacket around the 
stove? Is there any special arrangement for getting air in and out of 
the room? 

14. If the building is furnace heated, is there an outdoor air supply 
and is the inlet clean and unobstructed? 

15. Is there some means provided for moistening the air? 

16. Is the fresh air inlet removed from toilets or other sources of 
contamination? 

17. Are the schoolrooms free from unpleasant odors at all times? 

18. Are erasers cleaned every day out of doors? 

19. Are floors oiled or otherwise treated to keep down dust? 

20. Do you keep your temperatures even? 

21. Do you keep the room temperatures under 70° and over 60°? 

Halls 

22. Do you keep the halls of your building clean? 

23. Are the halls well heated? 

24. Are the halls well ventilated? 

25. Are the halls free from obstructions? 

Basement 

26. Are the floors clean and dry? 

27. Are the floors made of cement? 

28. Are wash basins and sinks clean? 

99 



100 A Short Course for Janitor-Engineers 

29. Are toilets clean and well ventilated? 

30. Is the air wholesome? 

31. Are toilets well shut off from air intakes? 

School Environment 

32. Is the ground well drained? 

33. Are tin cans and other receptacles in which water might col- 
lect kept picked up? 

34. Are other breeding places of mosquitoes destroyed? 

35. Is garbage of all kinds properly destroyed? 

36. Is manure and other refuse hauled away as fast as it collects? 

37. Are the garbage cans in the neighborhood kept covered? 

38. Do you clearly understand that all such refuse as the above 
furnishes a breeding place for flies and that flies are dangerous carriers of 
disease? 

39. Is the drinking water clean? 

40. Is there any chance for the drinking water to be contaminated 
by sewage? 

41. Are there relatively few flies about the building? 

42. Are the vacant lots nearby kept clean? 



Brief List of Valuable Books for 
Janitor-Engineers 

School Janitors, Mothers and Health, Putnam. 

American Academy of Medicine Press, Easton, Pa. 

Report of the Chicago Commission on Ventilation. 
Department of Health, Chicago, Illinois. 

Standard Practical Plumbing, Starbuck. 

Norman W. Henley Publishing Co., New York City. 

Johnson's Handy Manual of Plumbing, Heating and Ventilating. 
Domestic Engineering, Chicago, 111. 

The Sanitary Sewerage of Buildings, Ainge. 
Domestic Engineering, Chicago, 111. 

The Warm Air Furnace Handbook. 

Peck Williamson Co., Cincinnati, Ohio. 

Heating and Ventilation. 

B. F. Sturtevant Co., Boston, Mass. 

Fuel Economy in the Operation of Hand-Fired Power Plants. 

Bulletin Engineering Experiment Station, University of Illinois, 
Urbana, Illinois. 



101 



INDEX 



Air circulation for radiators, 56 

Air distribution, 62 

Air, good and bad, 59 

Air, introducing moisture into, 82, 8.3 

Air space requirements, 61 

Air supply requirements, 62 

Air temperature, 8 

Air values, 52 

Air washers, 83 

Air, water carrying capacity, 76 

Alternate firing method, 39 

Analysis of coals, 27 

Anthracite coal, 26, 27 

Aspiration method of ventilation, 63 

Banking fire, 45 

Bins, calculation of size, 29 

Bituminous coal, 26, 27 

Boiler, boiling out, 48 

Boiler, laying up, 50 

Boiler, operation of, 47 

Boiler scale, removal, 49 

Boiler, washing of, 48 

Book list for janitor-engineers, 101 

British Thermal Unit, 10 

By-pass damper, 67 

Calculating sizes of coal bins, 29 

Carbon dioxide, 32 

Catechism for janitors, 99 

Centigrade thermometer, 7; scale, 9 

Chicago Ventilating Commission's Conclusions on Heating 

and Ventilation, 72; Conclusions on Humidity and 

Temperature, 84 
Cleaning methods, 88 
Clinkers, prevention of, 45 
Coal, analysis of, 27 
Coal and combustion, 24 
Coal, composition, 24 

103 



104 Index — Continued 

Coal, names and sizes, 29 
Coal storage, 30 
Coke, 29 

Coking method of firing, 40 
Combustion, 30 
Combustion of coal, 33 
Conduction of heat, 16 
Convection of heat, 16 

Deodorants, 93 

Diaphragm valves, 55 

Direct and indirect heating systems, 55 

Direct fan system, 65 

Direct-indirect fan system, 67 

Disinfectants, 90 

Disinfecting methods, 91 

Disinfection, prescribed by health authorities, 92 

Draft, control of, 43 

Dusting, 90 

Duties of janitors, 7 

Effects of heat, 12 

Effects of high and low humidity, 79 

Fahrenheit thermometer, 7; scale, 9 

Fan system, 65 

Fan systems, operation, 70 

Fire, banking of, 45 

Fire, how to maintain, 41 

Firing, 35 

Firing methods, 39 

Firing, special methods and appliances, 41 

Fixed carbon, 25 

Float valve, 53 

Furnace and combustion, 32 

Heat, effects of, 12 

Heat, effect on water, 13 

Heat measurement, 9, 10 

Heat, rate of travel, 20 

Heat, theory of, 7 

Heat travel, circumstances affecting, 17 

Heat, travel of, 14 



Index — Continued 105 

Heat, units in elements, 33 

Heating coils, 67 

Heating plant, 47 

Heating plant, definitions, 51 

Heating systems, 50 

Heating value of coal, 27 

Humidity, 74 

Humidity, effects of, 79 

Humidity, measuring of, 80 

Humidity, relation to temperature, 77 

Humidity table, 78 

Indirect fan system, 65 

Janitor, duties of, 7 
Janitor's catechism, 99 

Latent and sensible heat, 20 
Laying up a boiler, 50 

Measuring humidity, 80 

Mechanical ventilation, 63 

Methods of firing, 39 

Mixing dampers, 67 

Moisture content of air at varying temperatures, 76 

Moisture, introducing in air, 82, 83 

Names and sizes of coal, 29 
Natural and aspiration systems, 68 
Natural ventilation, 63, 69 

Plenum room, 67 

Radiation, 16, 19 

Radiators, placing of, 55 

Rate of heat travel, 20 

Recirculation of air at night, 57 

Relative and absolute humidity, 75 

Room temperature, 8 

Rules and regulations for cleaning and care of buildings and 

grounds, 94 
Rules for building care, 97 

Sanitation, 90 
Scale, boiler, 49 



1 OG / ndex — Concluded 

Semi-bituminous coal, 20, 27 

Sling psychrometer, 81, 82 

Smoke, causes, 37 

Smoke prevention, 35 

Specific heat tables, 1 1 

Spreading method of firing, 39 

Steam heating, 52 

Steam jets, 68 

Steam table, 21 

Storage of coal, rules for, 30 

Sulphur dioxide, 32 

Sweeping, 86 

Sweeping and cleaning, 80 

Sweeping compound, 88 

Temperature, requirements, 03 

Temperature tables, 9 

Tempering coils, 67 

Thermometer, dry bulb, 81; wet bulb, 81 

Thermometers, 7 

Thermostatic value, 53 

Thermostats, 55 

Vacuum and vapor systems, 53 
Ventilation systems, 63 

Warm air heating systems, 56 

Washing boiler, 48 

Water, moisture, 84 

Water, heating qualities, 13 

Water pans, 84 

Water pounding, 53 

Winter care of school buildings, 98 

Woodwork polish, 89 



